PLATE X

Polariscope.]

ARTOTYPE. E. BIERSTADT N. Y.

If a ray of common light be made to pass through certain crystals, such as calc spar, it undergoes double refraction, and the light transmitted becomes polarised. The arrangement known as Nicol’s prism, which consists of two prisms of calc spar, cut at a certain angle and united together by means of Canada balsam, is a very convenient means of obtaining polarised light. If two Nicol’s prisms are placed in a similar position, one behind the other, the light polarised by the first (or polarising) prism passes through the second (or analysing) prism unchanged; but if the second prism be turned until it crosses the first at a right angle, perfect darkness ensues. While it would exceed the limits of this work to enter fully upon the theoretical explanations which are commonly advanced concerning the cause and nature of this polarised, or transformed light, it may be well to state here that common light is assumed to be composed of two systems of beams which vibrate in planes at right angles to each other, whereas polarised light is regarded as consisting of beams vibrating in a single plane only. If, now, we imagine the second Nicol’s prism to be made up of a series of fibres or lines, running only in one direction, these fibres would act like a grating and give free passage to a surface like a knife blade only when this is parallel to the bars, but would obstruct it if presented transversely. This somewhat crude illustration will, perhaps, serve to explain why the rays of light which have been polarised by the first Nicol’s prism are allowed to pass through the second prism when the two are placed in a similar position, and why they are obstructed when the prisms are crossed at right angles, it being remembered that in a polarised ray the vibrations of the beams of light take place in a single plane.

Suppose we place between the two Nicol’s prisms, while they are at right angles, a plate cut in a peculiar manner from a crystal of quartz, we will discover that rays of light now pass through the second prism, and that the field of vision has become illuminated with beautiful colours--red, yellow, green, blue, etc., according to the thickness of the quartz plate used. On _turning_ the second Nicol’s prism on its axis, these colours will change and pass through the regular prismatic series, from red to violet, or the contrary, according to the direction of the rotation produced by the intervening plate. Quartz, therefore, possesses the remarkable property of rotating the plane of polarisation of the coloured rays of which light is composed; and it has been discovered that some plates of this mineral exert this power to the right, others to the left; that is, they possess a right or left-handed circular polarisation. Numerous other substances, including many organic compounds, possess this quality of causing a rotation--either to the right or left--of a plane of polarised light. For example, solutions of cane sugar and ordinary glucose cause a right-handed rotation, whilst levulose and invert sugar exert a left-handed rotation. The extent of this power is directly proportional to the concentration of the solutions used, the length of the column through which the ray of polarised light passes being the same. It follows that on passing polarised light through tubes of the same length which are filled with solutions containing different quantities of impure cane sugar, an estimation of the amount of pure cane sugar contained in the tubes can be made by determining the degree of right-handed rotation produced; and it is upon this fact that the application of the polariscope in sugar analysis is based. The optical portions of the most improved form of the polariscope--that known as the Ventzke-Scheibler--are represented by Fig. 2.

The light from a gas burner enters at the extremity of the instrument and first passes through the “regulator A,” which consists of the double refracting Nicol’s prism _a_ and the quartz plate _b_, it being so arranged that it can be turned round its own plane, thus varying the tint of the light used, so as to best neutralise that possessed by the sugar solution to be examined. The incident ray now penetrates the polarising Nicol’s prism B, and next meets a double quartz plate C (3·75 millimetres in thickness). This quartz plate, a front view of which is also shown in the figure, is divided in the field of vision, one half consisting of quartz rotating to the right hand, the other half of the variety which rotates to the left hand. It is made of the thickness referred to owing to the fact that it then imparts a very sensitive tint (purple) to polarised light, and one that passes very suddenly into red or blue when the rotation of the ray is changed. Since the plate C is composed of halves which exert opposite rotary powers, these will assume different colours upon altering the rotation of the ray. After leaving the double quartz plate the light, which, owing to its passage through the Nicol’s prism B is now polarised, enters the tube D containing the solution of cane sugar under examination; this causes it to undergo a right-handed rotation. It next meets the “compensator” E, consisting of a quartz plate _c_, which has a right-handed rotary power, and the two quartz prisms _d_, both of which are cut in a wedge shape and exert a left-handed rotation. They are so arranged that one is movable and can be made to slide along the other, which is fixed, thus causing an increase or decrease in their combined thickness and rotary effect. The ray of light then passes through the analysing Nicol’s prism F, and is finally examined by means of the telescope G, with the objective _e_ and ocular _f_. Fig. 3 gives a perspective view of the Ventzke-Scheibler polariscope. The Nicol’s

In the practical use of the Ventzke-Scheibler saccharimeter the method to be followed is essentially as follows: 26·048 grammes of the sugar to be tested are carefully weighed out and introduced into a flask 100 cubic centimetres in capacity; water is added, and the flask shaken until all crystals are dissolved. The solution is next decolorised by means of basic plumbic acetate, its volume made up to 100 cubic centimetres, and a little bone-black having been added if necessary, a glass tube, corresponding to P (Fig. 3) which is exactly 200 millimetres in length, and is provided with suitable caps, is completely filled with the clear filtered liquid. This is then placed in the polariscope, and protected from external light by closing the cover shown at _h´_. On now observing the field of vision by means of the telescope, it will be seen that the halves into which it is divided exhibit different colours. The screw M is then turned to the right until this is no longer the case, and absolute uniformity of colour is restored to the divisions of the double quartz plate C (Fig. 2). The extent to which the screw has been turned, which corresponds to the right-handed rotation caused by the sugar solution, is now ascertained on reading the scale by the aid of the glass K. The instrument under consideration is so constructed that, when solutions and tubes of the concentration and length referred to above are used, the reading on the scale gives directly the percentage of pure crystallisable cane sugar contained in the sample examined. For instance, if the zero index of the fixed scale points to 96°·5 on the movable scale, after uniformity of colour has been obtained, the sample of sugar taken contains 96·5 per cent. of pure cane sugar. The results given by the polariscope possess an accuracy rarely, if ever, attained by any other apparatus employed in the determination of practical commercial values.[57]

The proportion of grape sugar intentionally added to cane sugar can also be determined by the use of the polariscope, certain modifications being observed in its application. As previously stated, cane sugar is converted into a mixture of dextrose and levulose, termed invert sugar, by the action of dilute acids. While the rotary effect of dextrose upon the plane of a ray of polarised light is constant at temperatures under 100°, that exerted by levulose varies, it being reduced as the temperature is increased; hence it follows that at a certain temperature the diminished levo-rotary power of the levulose will become neutralised by the dextro-rotary effect of the dextrose, _i.e._ the invert sugar will be optically inactive. This temperature has been found to approximate 90°. Since dextrose is not perceptibly affected by the action of weak acids, it is evident that by converting cane sugar into invert sugar and examining the product by the polariscope at a temperature of about 90°, the presence of any added dextrose (glucose) will be directly revealed by its dextro-rotary action. This is accomplished by a method suggested by Messrs. Chandler and Ricketts,[58] which consists in substituting for the ordinary observation tube of the polariscope a platinum tube, provided with a thermometer, and surrounded by a water-bath, which is heated to the desired temperature by a gas burner (Plate X. Fig. 4). The sugar solution to be examined is first treated with a little dilute sulphuric acid, then neutralised with sodium carbonate, clarified by means of basic plumbic acetate, filtered, and the polariscopic reading taken at a temperature of 86° to 90°.

Since the results given by the foregoing method represent pure dextrose, it is necessary to first ascertain the dextro-rotary power of the particular variety of glucose probably employed for the adulteration of the sugar under examination, and then make the requisite correction. This process for the estimation of glucose is especially advantageous, in that the optical effect of the invert sugar normally present in raw cane sugars is rendered inactive.

It is sometimes desirable to determine the relative proportions of the organic constituents which are present in commercial glucose. These usually consist of dextrose, maltose, and dextrine, all of which possess dextro-rotary power, but not in the same degree; that of dextrose being 52, that of maltose 139, and that of dextrine 193. An estimation of the amount of each can be made by first ascertaining the total rotary effect of the sample by means of the polariscope.[59] This is expressed by the equation

P = 52 _d_ + 139 _m_ + 193 _d´_, (1)

in which P is the total rotation observed. Upon now treating the solution of glucose with an excess of an alkaline solution of mercuric cyanide (prepared by dissolving 120 grammes of mercuric cyanide and 25 grammes of potassium hydroxide in 1 litre of water), the dextrose and maltose contained in the sample are decomposed, leaving the dextrine unaffected. A second polariscopic reading is then made, which gives the amount of dextrine present, that is

P´ = 193 _d´_, (2)

from which the proportion of dextrine is calculated.

Subtracting the second equation from the first, we have

P - P´ = 52 _d_ + 139 _m_. (3)

Both dextrose and maltose reduce Fehling’s solution, the total reduction (R) being the reducing per cent. of the former (_d_) added to that of the latter (_m_). The reducing power of maltose is, however, only 0·62 as compared with dextrine, therefore

R = _d_ + 0·62 _m_. (4)

Multiplying by 52, we have

52 R = 52 _d_ + 32·24 _m_,

and subtract from (3), which gives

P - P´ - 52 R = 106·76 _m_, (5)

_m_ = (P - P´ - 52 R) / 106·76 (6)

_d_ = R - 0·62 _m_ (7)

_d´_ = P´/193.

FOOTNOTES:

[54] It is of interest in this connection to note the recent discovery of a coal-tar derivative, benzoyle sulphonic imide, C_{6}H_{4} <CO/SO> NH, commercially known as “saccharine.” This body possesses about 230 times the sweetening power of cane sugar. It bears, however, no near chemical relation to the sugars, which, for the greater part, constitute hexatomic alcohols. See Amer. Chem. Jour., i. p. 170, and vol. ii. p. 181; also, Jour. Soc. Chem. Indus., No. 2, vol. vi. p. 75.

[55] Of 41 samples of molassan, tested in Massachusetts in 1885, 12 contained tin chloride.

[56] The average composition of over 100,000 samples of raw cane sugar (mostly Cuban) tested in the United States Laboratory during the past five years, has been as follows:--

Per cent. Moisture 3·0 Ash 1·5 Polarisation 90°

[57] The foregoing description of the polariscope was embodied in an article contributed by the author to Van Nostrand’s Engineering Magazine.

[58] Journ. Amer. Chem. Soc., i. p. 1.

[59] Wiley, Chem. News, xlvi. p. 175.

Honey consists of the saccharine substance collected by the bee (_Apis mellifica_) from the nectaries of flowers, and deposited by them in the cells of the comb. “Virgin honey” is the product of hives that have not previously swarmed, which is allowed to drain from the comb; the inferior varieties being obtained by the application of heat and pressure. As a result of the peculiar conditions of its formation, honey constitutes a rather complex mixture of several bodies; indeed, its exact composition is a matter of some doubt. The chief ingredients are levulose and dextrose, accompanied by a small amount of cane sugar, and inconsiderable proportions of pollen, wax, and mineral matter. According to Dubrunfaut and Soubeiran,[60] genuine honey contains an excess of levulose mixed with dextrose and some cane sugar. In the course of time the latter is gradually converted into invert sugar, and a crystalline deposit of dextrose forms, the levulose remaining fluid.

The following analyses made by J. C. Brown[61] and E. Sieben,[62] show the general composition of pure honey:--

------------------------+----------------+---------------- | J. C. Brown. | E. Sieben. ------------------------+----------------+---------------- Dextrose | 31·77 to 42·02 | 22·23 to 44·71 Levulose | 33·56 „ 40·43 | 32·15 „ 46·89 Total glucoses | 68·40 „ 79·72 | 67·92 „ 79·57 Sucrose | .. | none „ 8·22 Wax, pollen and insol | trace to 2·10 | .. Ash | 0·07 „ 0·26 | .. Water at 100° | 15·50 „ 19·80 | 16·28 to 24·95 Undetermined | 4·95 „ 11·00 | 1·29 „ 8·82 ------------------------+----------------+----------------

Barth has examined several varieties of genuine honey with the following results:--

-----------------------------------+----------+-----------+----------- | Per cent.| Per cent. | Per cent. -----------------------------------+----------+-----------+----------- Water | 13·60 | 15·60 | 11·06 Dry substance | 86·40 | 84·40 | 88·94 Ash | 0·28 | 0·24 | 0·90 Polarisation of 10 per }Direct | -4·6° | -5° | +11° cent. solution (in 200 }After | | | millimetre tube) } inversion| .. | -7·5° | +4° {Original substance | 69·60 | 72·0 | 60·0 Sugar {After inversion | 69·50 | 77·0 | 74·6 Organic matter, not sugar | 16·52 | 7·16 | 13·44 -----------------------------------+----------+-----------+-----------

W. Bishop[63] obtained the following figures from the examination of honey of known purity:--

-----------------------------+-----------+-------+---------+--------- |Hungarian. |Chili. |Italian. |Normandy. -----------------------------+-----------+-------+---------+--------- Reducing sugar | 67·17 | 73·05 | 70·37 | 79·39 Crystallised sugar | 7·58 | 4·55 | 5·77 | 0· Direct polarisation | -13·70 |-14·15 | -8·55 | -9·25 Polarisation after inversion | -15·40 |-14·85 | -12·0 | .. -----------------------------+-----------+-------+---------+---------

The substances said to be employed in the adulteration of honey are water, starch, cane sugar, and glucose-syrup; the last mentioned is undoubtedly most commonly used. Hager[64] states that, by treating corn starch with oxalic acid, a product is obtained which, on standing two or three weeks, acquires the appearance and taste of genuine honey; and samples of commercial honey not unfrequently wholly consist of this or some other form of artificial glucose. The season for the collection of honey by bees is a limited one, and any existing deficiency in their natural source of supply is sometimes remedied by placing vessels filled with glucose near the hives. Occasionally the bees are also supplied with a ready-made comb, consisting, at least partially, of paraffine. It has been asserted that in some instances, this factitious comb is entirely composed of paraffine, but the writer is informed that, if the sophistication is practised to a proportion of over 10 per cent., the bees do not readily deposit the honey in the comb.

Owing to the complex composition of honey and to the rather incomplete character of the analyses of the genuine article at hand, the detection of some of the forms of adulteration resorted to is a matter of considerable difficulty. The presence of starch is best recognised by the microscopic examination of the honey. This will likewise reveal the absence of pollen, which may be regarded as a certain indication of the spurious nature of the sample. There appears to exist a difference of opinion in regard to the presence of cane sugar in genuine honey, but it may safely be accepted that the detection of a considerable proportion of this substance points to its artificial addition. In all cases of suspected adulteration with cane sugar or glucose, the determination of the sugar present by means of the polariscope and by Fehling’s method (both before and after inversion) is indispensable. It is commonly stated that unsophisticated honey polarises to the left, and that a sample possessing a dextro-rotary action is necessarily contaminated with glucose or cane sugar; but, while in the great majority of cases this is doubtless the fact, it is equally certain that honey of known purity has been met with which polarised to the right. Upon the inversion of honey containing cane sugar, the dextro-rotation is changed to a levo-rotation.

According to Lenz,[65] the specific gravity (at 17°) of a solution of 30 grammes of pure honey in exactly twice the quantity of distilled water is never less than 1·1110, a lower density indicating adulteration with water. Hehner[66] states that the ash of genuine honey is always alkaline, whereas that of artificial glucose is invariably neutral. The proportion of phosphoric acid present in honey varies from 0•·013 to 0•·035 per cent., which is considerably less than the proportion contained in starch sugars. Honey contaminated with starch sugar will generally show about 0·•10 per cent. of phosphoric acid, and artificial honey, made from cane sugar, will usually be free from the acid.

The addition of commercial glucose may often be detected by the turbidity produced upon adding ammonium oxalate to a filtered aqueous solution of the sample; this is due to the presence of calcium sulphate, a common impurity in the commercial varieties of glucose. If the glucose employed for admixture contains much dextrine, as is very often the case, this fact can be utilised in its detection as follows:--2 c.c. of a 25 per cent. solution of the honey are introduced into a narrow glass cylinder, and 0·•5 c.c. of absolute alcohol is cautiously added; with pure honey, the point of contact of the liquids will remain clear or become so upon allowing the mixture to stand at rest, whereas in presence of artificial glucose a milky turbidity will appear between the two strata. Genuine honey may, it is true, contain a small proportion of dextrine and exhibit a slight cloudiness when treated with alcohol, but the difference in the degree of turbidity caused is very considerable, and sufficient to render the test of service.

The test may also be applied by dissolving 20 grammes of the suspected honey in 60 c.c. of distilled water and then adding an excess of alcohol. Under these circumstances pure honey merely becomes milky, while, if commercial glucose is present, a white precipitate of dextrine is formed, which can be collected and weighed. If the sugar in the sample is determined by Fehling’s solution, both before and after inversion with a little sulphuric acid, and an estimation of the amount of dextrine present is made by precipitation with alcohol, it often occurs that the quantity of the latter substance is proportional to the difference between the amount of sugar found.

According to the late investigations of Sieben,[67] fairly satisfactory methods for the detection and determination of glucose syrup in honey are based upon the following facts:--

1st. When genuine honey undergoes fermentation, the substances which remain undecomposed, are optically inactive. Glucose, or starch syrup, on the other hand, leaves a considerable amount of dextrine, which is strongly dextrogyrate. The test is made by dissolving 25 grammes of honey in about 160 c.c. of water, and adding 12 grammes of yeast (free from starch). The mixture is allowed to ferment at a moderate temperature for two or three days, after which aluminium hydroxide is added, and the liquid made up to 250 c.c. and then filtered. 200 c.c. of the filtrate are evaporated to a volume of 50 c.c., and a 200 mm. tube is then filled with the concentrated solution and examined by the polariscope.

2nd. The substances remaining unaffected by the fermentation of pure honey are not converted into a reducing sugar by boiling with dilute hydrochloric acid, as is the case with those obtained from starch syrup under the same circumstances. 25 c.c. of the solution employed for the polarisation test, as just described, are diluted with an equal volume of water, 5 c.c. of strong hydrochloric acid added, and the mixture is placed in a flask and heated for an hour over the water-bath. The contents of the flask are neutralised with potassium hydroxide, then diluted to a volume of 100 c.c., and the proportion of reducing sugar estimated in 25 c.c. of the solution. Honey containing different proportions of starch sugar gave the following percentages of reducing sugar:--

Starch-Sugar Present. | Reducing Sugar Obtained. per cent. | per cent. 5 | 1·472 10 | 3·240 20 | 6·392 40 | 8·854

3rd. If the cane sugar originally present in genuine honey has been changed into invert sugar, and the honey solution is boiled with a slight excess of Fehling’s reagent, no substances capable of yielding sugar when treated with acids will remain undecomposed. Starch syrup, when subjected to this treatment, yields grape sugar in about the proportion of 40 parts to every 100 parts of the syrup used. The test is applied as follows:--14 grammes of honey are dissolved in 450 c.c. of water, and the solution is heated over the steam-bath with 20 c.c. of semi-normal acid, in order to invert the cane sugar present. After heating for half an hour, the solution is neutralised, and its volume made up to 500 c.c. 100 c.c. of Fehling’s solution are then titrated with this solution, which may contain about 2 per cent. of invert sugar (in case the sample examined is pure, from 23 to 26 c.c. will be required); 100 c.c. of Fehling’s reagent are next boiled with 0·5 c.c. less of the honey solution than was found to be necessary to completely reduce the copper. The reduced liquid is then passed through an asbestos filter, the residue washed with hot water, the filtrate treated with a slight excess of concentrated hydrochloric acid, and the solution heated for one hour on the steam-bath. Sodium hydroxide is now added, until only a very little free acid remains unneutralised, and the solution is made up to 200 c.c. Upon well shaking the cooled liquid, a deposit of tartar sometimes separates. 150 c.c. of the filtered solution are finally boiled with a mixture of 120 c.c. of Fehling’s reagent and 20 c.c. of water, and the proportion of grape sugar estimated from the amount of metallic copper obtained. (See p. 111.) When pure honey is submitted to the preceding process, the copper found will not exceed 2 milligrammes. The quantities of copper obtained when honey adulterated with various proportions of starch sugar was tested were about as follows:--

Starch Sugar | Milligrammes of contained. | Copper found. per cent. | 10 | 40 20 | 90 30 | 140 40 | 195 50 | 250 60 | 330 70 | 410 80 | 500

--------------------------------+----------------------------------- |Dextrose. | +---------------------------- | |Levulose. | | +--------------------- | | |Invert Sugar, Character of Samples. | | | by Fehling’s Method. | | | +------------- | | | |Cane Sugar. | | | | +------ | | | | |Total | | | | |Sugar. --------------------------------+------+------+-------+------+------ | per | per | per | per | per |cent. |cent. | cent. | cent.| cent. Adulterated with cane sugar | .. | .. | 56·39 | 19·45| 76·84 „ „ „ „ and | | | | | water |25·63 |25·42 | 51·06 | 10·62| 61·67 „ „ 15 per cent. | | | | | glucose syrup|37·20 |31·80 | 69·18 | .. | 69·00 „ „ 65 per cent. | | | | | glucose syrup|21·75 |19·60 | 41·30 | .. | 41·35 „ „ 40 per cent. | | | | | glucose syrup|34·61 |23·89 | 58·83 | .. | 58·50 „ „ 40 per cent. | | | | | glucose syrup| | | | | and with cane| | | | | sugar. |25·47 |23·51 | 49·04 | 7·06| 56·04 „ „ 80 per cent. | | | | | glucose syrup|21·92 |12·83 | 35·00 | .. | 34·75 --------------------------------+------+------+-------+-------------

--------------------------------+------------------------- |Water. | +------------------ Character of Samples. | |Dry Substance. | | +----------- | | | Not Sugar. --------------------------------+------+------+----------- | per | per | per |cent. |cent. |cent. Adulterated with cane sugar |20·85 |79·15 | 2·31 „ „ „ „ and | | | water |36·48 |63·52 | 1·85 „ „ 15 per cent. | | | glucose syrup|18·54 |81·46 |12·46 „ „ 65 per cent. | | | glucose syrup|18·65 |81·35 |40·00 „ „ 40 per cent. | | | glucose syrup|17·81 |82·19 |23·69 „ „ 40 per cent. | | | glucose syrup| | | and with cane| | | sugar. |19·94 |80·06 |24·02 „ „ 80 per cent. | | | glucose syrup|18·12 |81·88 |57·13 --------------------------------+------+------+-----------

--------------------------------+--------+---------------------------- |Polarisation after Fermentation. | +---------------------------- | I |Residue of Fermentation when | |treated with acid gave Grape Character of Samples. | | Sugar. | | +------------------ | | |Milligrammes of | | |Copper found by | | |Method 3. --------------------------------+--------+---------+------------------ |degrees.|per cent.| mgr. Adulterated with cane sugar | 0·0 | 0·0 | 0 „ „ „ „ and | | | water | 0·0 | 0·0 | 0 „ „ 15 per cent. | | | glucose syrup| × 4·4 | 4·2 | 66 „ „ 65 per cent. | | | glucose syrup| × 25 | 12·4 | 366 „ „ 40 per cent. | | | glucose syrup| × 13 | 7·6 | 196 „ „ 40 per cent. | | | glucose syrup| | | and with cane| | | sugar. | | | „ „ 80 per cent. | | | glucose syrup| × 34 | 15·2 | 492 -----------------------------------------+---------+------------------

The tabulation on p. 127 exhibits the results obtained by the application of the foregoing tests to adulterated honey.[68]

The detection of paraffine in honeycomb is easily accomplished. Genuine bees’-wax fuses at 64°, paraffine usually at a lower temperature. The latter is not affected by treatment with concentrated sulphuric acid, whereas bees’-wax is dissolved by the strong acid, and undergoes carbonisation upon the application of heat. The amount of potassium hydroxide required for the saponification of one gramme of bees’-wax, as applied in Koettstorfer’s method for butter analysis (p. 71), widely differs from the quantities consumed by Japanese wax and paraffine. Mr. Edward W. Martin has obtained the following figures:--

Milligrammes K (O H) required to saponify one gramme. Bees’-wax 7·0 Japanese wax 212·95 Paraffine none

18 out of 37 samples of strained and comb honey, examined in 1885 by the Mass. State Board of Health, were adulterated with glucose and ordinary syrup.

FOOTNOTES:

[60] ‘Comptes Rendus,’ xxviii. p. 775.

[61] ‘Analyst,’ iii. p. 269.

[62] Zeits. Anal. Chem., xxiv. p. 135.

[63] Journ. de Pharm. et de Chem., 1884, p. 459.

[64] Pharm. Centralb. 1885, pp. 303, 327.

[65] ‘Chemiker Zeitung,’ viii., p. 613.

[66] ‘Analyst,’ x., p. 217.

[67] Zeitsch. d. Vereins. f. d. Rübenzucker Ind., p. 837.

[68] ‘Jahresberichte,’ 1884, p. 1051.

CONFECTIONERY.

Pure white candy should consist entirely of cane sugar with its water of crystallisation, but most of the article commonly met with contains a large proportion of glucose, and in many cases it is wholly composed of this compound (see p. 109). Starch and terra alba (_i. e._ gypsum or kaolin), are the other adulterants sometimes employed to fraudulently increase the bulk and weight of candy.

The substances used for colouring purposes are more liable to be positively deleterious. While such colouring agents as caramel, turmeric, litmus, saffron, beet-juice, indigo, and some of the coal-tar dyes may be considered comparatively harmless, there can be no question in regard to the very objectionable character of certain other pigments which are sometimes employed: these are mainly inorganic, and include plumbic chromate, salts of copper and arsenic, zinc-white, barium sulphate and Prussian blue. Another occasional form of adulteration to which some kinds of confectionery are exposed, is the admixture of artificial flavourings, such as “pear essence” (amylic and ethylic acetates), “banana essence” (a mixture of amylic acetate and ethylic butyrate), and oil of bitter almonds, or its imitation, nitro-benzole. A preparation known as “rock and rye drops,” which had acquired a great popularity among school children in several of our large cities, proved upon analysis to consist of a mixture of glucose, flour, and fusel oil.

The examination of candy and other forms of confectionery usually embraces the determinations of glucose, starch, flour, colouring and flavouring agents, terra alba, and mineral admixtures generally. The detection and estimation of glucose has already been described under Sugar.

Starch and flour are readily detected upon treating a minute portion of the suspected candy with a little water and submitting the mixture to a microscopic examination, when, in their presence, the insoluble residue will exhibit the characteristic forms of starch granules. The insoluble portion of the sample may also be tested with a solution of iodine. The proportion of starch can be determined by boiling the matter insoluble in water with dilute sulphuric acid, and estimating the amount of glucose found, by means of Fehling’s solution.

Coal-tar and vegetable compounds used for colouring purposes, can often, be recognised by means of their behaviour with reducing and oxidising agents, by their solubility in spirits and other menstrua, and by the application of dyeing-tests. Thus vegetable colours may sometimes be identified upon boiling mordanted cotton yarn in a bath prepared from a portion of the sample containing the colouring matter, and slightly acidulated with acetic acid. This process will likewise generally reveal the presence of aniline dyes, unmordanted woollen cloth being substituted for cotton, and a neutral bath being employed. The inorganic pigments used for colouring candy are usually to be sought for in the ash obtained upon incineration.

The presence of copper and lead is detected by the formation of black precipitates upon saturating with sulphuretted hydrogen the solution of the ash in hydrochloric acid; zinc, chromium, etc., are precipitated from the filtered solution upon addition of ammonium hydroxide and ammonium sulphide. It is frequently more convenient to apply special tests for the particular metal thought to be present, either directly to the pigment or to the ash. In this way, arsenic can often be recognised by treating a portion of the colouring matter in a test-tube, when it will sublime and collect upon the cool part of the tube in minute crystals of arsenious acid. Or, an acidulated solution of the detached pigments may be boiled with a piece of polished copper-foil, upon which the arsenic will be deposited as a greyish film: this can be sublimed, and otherwise further examined.

Copper is easily detected and estimated by placing the acid solution of the ash in a tared platinum dish, and reducing the copper by the electrolytic method. Chromium is recognised upon boiling the colouring matter with potassium carbonate solution: in its presence, potassium chromate is formed, which is submitted to the usual distinctive tests for chromium. The colour of Prussian blue is destroyed upon warming it with caustic alkalies: indigo, which remains unaffected by this treatment, forms a blue solution if heated with concentrated sulphuric acid. The presence of terra alba, barium sulphate, etc., is best detected by the examination of the ash. Chalk, or marble-dust, is recognised by its effervescence when treated with an acid, as well as by the presence of a notable proportion of lime in the ash.

Many of the flavouring mixtures added to candy may be separated by treating the sample with chloroform or petroleum naphtha and evaporating the solution to dryness over a water-bath, when their identity is frequently revealed by their odour and other physical properties. Of 198 samples of the cheaper varieties of confectionery examined by Health officials in the United States, 115 were adulterated. Plumbic chromate is a very common addition; 41 out of 48 samples of yellow- and orange-coloured candy contained this poisonous pigment.

The name beer is most commonly applied to a fermented infusion of malted barley, flavoured with hops. Its manufacture embraces two distinct operations, _viz._, malting and brewing. Briefly considered, the former process consists in first steeping barley (the seed of _Hordeum distichon_) in water and allowing it to germinate by arranging it in layers or heaps which are subsequently spread out and repeatedly turned over, the germination being thereby retarded; it is afterwards entirely checked by drying the grain (now known as _malt_) in cylinders or kilns.

The degree of temperature employed in drying and roasting the barley determines the colour and commercial character of the malt, which may be pale, amber, brown or black. In the United States the light-coloured varieties of malt are chiefly made. An important change which takes place during the malting of barley is the conversion of its albuminous constituents into a peculiar ferment, termed _diastase_, which, although its proportion in malt does not exceed 0·003 per cent., exerts a very energetic action in transforming starch, first into dextrine, then into sugar (maltose). The following analyses, by Proust, exhibit the general composition of unmalted and malted barley:--

----+---------------------+---------------+-------------+---- | | Barley. | Malt. | | +---------------+-------------+ | Hordeine | 55 | 12 | | Starch | 32 | 56 | | Gluten | 3 | 1 | | Sugar | 5 | 15 | | Mucilage | 4 | 15 | | Resin | 1 | 1 | | | --- | --- | | | 100 | 100 | ----+---------------------+---------------+-------------+----

The body termed hordeine is generally considered to be an allotropic modification of starch.

In the brewing of beer, the malted grain is crushed by means of iron rollers, and then introduced into the mash-tubs and digested with water at a temperature of about 75°, whereby the conversion of the starch into dextrine and sugar is effected. After standing for a few hours, the clear infusion, or _wort_, is drawn off and boiled with hops (the female flower of _Humulus lupulus_), after which it is rapidly cooled, and then placed in capacious vats where it is mixed with yeast and allowed to undergo the process of fermentation for several days, during which the formation of fresh quantities of yeast and a partial decomposition of the sugar into alcohol and carbonic acid take place. The beer is next separated from the yeast and transferred into clearing-vats, and, later on, into storage casks, where it undergoes a slow after-fermentation, at the completion of which it is ready for consumption. The quality of the water used in the process of mashing and brewing is of great importance, and it is of special moment that it should be free from all organic contaminations. The presence of certain mineral ingredients, notably of calcium sulphate, is believed to exert a beneficial effect on the character of the beer obtained.

In the United States, the best known varieties of malt liquors are ale, porter, and lager beer. The difference between ale and porter is mainly due to the quality of the malt used in their manufacture. Ale is made from pale malt, porter or stout from a mixture of the darker coloured malts, the method of fermentation employed being in both cases that known as the “superficial” (_obergährung_), which takes place at a higher temperature and is of shorter duration than the “sedimentary” (_untergährung_). The latter form of fermentation, which is used in the preparation of Bavarian or lager beer, occurs at a temperature of about 8°, and requires more time for its completion, during which the beer is, or should be, preserved in cool cellars for several months before it is fit for use; hence the common American name of this kind of beer, from _lager_, a storehouse. There are three varieties of Bavarian beer, “lager beer” proper, or the summer beer, which has been stored for about five months; “_schenk_,” or winter beer, which is fit for use in several weeks; and “_bock_” beer, which possesses more strength than the former, and is made in comparatively small quantities in the spring of the year. A mild kind of malt liquor, known as “_weiss_” beer, and prepared by a quick process of fermentation, is less frequently met with.

The first brewery in America is said to have been founded in New York in the year 1644, by Jacobus, who afterwards became the first burgomaster of the city, then New Amsterdam. Subsequently, William Penn established a brewery in Bucks Co., Pa., and a century later, General Putnam engaged in the manufacture of beer in the State of Connecticut. The brewing of lager beer in the United States began to assume prominence about thirty-five years ago. It is estimated that, at the present time, over 2000 breweries are devoted to the preparation of this form of malt liquor, with an invested capital of at least 60 millions of dollars, the annual production exceeding 15 millions of barrels.[69] The industry is chiefly carried on in New York, Brooklyn, Philadelphia, Milwaukee, St. Louis, and Cincinnati.

The composition of beer naturally varies according to the kind of grain from which it is made and the process of fermentation employed. The chief ingredients are alcohol, carbonic acid, sugar (maltose), dextrine, the oil and bitter principle of hops (lupuline), albuminoids, lactic, acetic, succinic and propionic acids, inorganic salts, and traces of glycerine. The term “extract” is applied to the non-volatile constituents, which include the sugar, dextrine, albuminoids, ash, etc. The foregoing table, collated from the analyses of various chemists, gives the general composition of some of the best known brands of malt liquor, as well as the minimum and maximum proportions that have been found.

--------------+------------------------------------------------------- |Specific Gravity. | +------------------------------------------------ | |Carbonic Acid. | | +------------------------------------------ | | |Alcohol (by weight). | | | +------------------------------------- | | | |Extract. | | | | +------------------------------- | | | | |Albuminoids. Variety. | | | | | +-------------------------- | | | | | |Sugar. | | | | | | +--------------------- | | | | | | | Dextrine. | | | | | | | +---------------- | | | | | | | |Phosphoric Acid. | | | | | | | +----------+ | | | | | | | |Acid. | | | | | | | | | +-----+ | | | | | | | | |Ash. | --------------+------+-----+----+-----+----+----+----+----+-----+----- | |p.c. |p.c.|p.c. |p.c.|p.c.|p.c.|p.c.|p.c. |p.c. Porter |1·0207|0·16 | 5·4| 6·0 |0·83| .. |7·72|0·24|0·40 | .. Scotch ale | .. |0·15 | 8·5|10·9 |0·77|0·34|2·50|0·19| .. | .. Burton ale |1·0106| .. | 5·9|14·5 |0·57| .. |3·64|0·32| .. | .. Munich | | | | | | | | | | (Salvator)|1·0129|0·18 | 4·6| 9·4 |0·67| .. | .. | .. | .. | .. „ (Bock) |1·0118|0·17 | 4·2| 9·2 | .. |0·80| .. | .. |0·22 |0·024 „ (Schenk) | .. | .. | 3·8| 5·8 | .. | .. |6·17|0·14| .. | .. „ (Lager) |1·0110|0·15 | 5·1| 5·0 |0·83|0·35| .. |0·20|0·21 | .. Berlin | .. | .. | 3·1| 5·8 | .. | .. | .. | .. |0·21 | .. „ (Tivoli) | .. | .. |4·35| 5·14| .. | .. | .. |0·23|0·19 | .. Erlanger | .. | .. |4·56| 4·81| .. |0·40|1·44| .. |0·48 | .. Thüringer | | | | | | | | | | (common) | .. | .. |2·00| .. | .. |0·31|7·71| .. | .. | .. Culmbacher |1·0228|

The composition of beer ash is evidently affected by the character of the water used in the brewing process. Blyth gives the following as the average composition of the ash of English beers:--

Per cent. Potash 37·22 Soda 8·04 Lime 1·93 Magnesia 5·51 Ferric oxide traces Sulphuric acid 1·44 Phosphoric acid 32·09 Chlorine 2·91 Silica 10·82

The following results were obtained by the writer from the analysis of the ash of American lager beer of fair quality:--

Per cent. Silica 9·97 Alumina and ferric oxide 0·46 Lime 3·55 Magnesia 7·27 Soda 13·81 Potassa 19·59 Sulphuric acid 3·25 Chlorine 4·40 Phosphoric acid 37·70 ------ 100·00

Percentage of ash 0·274

Strictly speaking, normal beer consists solely of the product of malt and hops, and the presence of any ingredients other than these should be regarded as an adulteration. It is maintained by brewers, and with justice, that the term “malt” is not necessarily restricted to barley, but includes other varieties of malted grain, such as wheat, corn, and rice. The old English law, while permitting the addition of wholesome bitters, prohibits the use of various other substances, but in the United States, no legal definition of pure beer has, as yet, been formulated, and the necessity for such a measure is being experienced.[70] The past literature of beer adulteration makes mention of very numerous substances which, in former times, have been resorted to as admixtures. Among these the following are the most prominent:--

1st. _Artificial bitters._--Picric acid, picrotoxine, aloes, gentian, quassia, and wormwood. Several years ago the author had occasion to examine two samples, imported under the name of “hop substitutes,” both of which proved to consist of _salicine_, the bitter principle of the willow. The fruit of the hop tree (_Ptelea trifoliata_), has also been employed as an artificial bitter for beer.

2nd. _Flavourings._--For flavouring purposes, cayenne pepper, “grains of paradise,” cloves, orris root, coriander seeds, the oils of anise, nutmegs, and carraway, are stated to have been used.

3rd. _Malt substitutes._--These mainly consist of corn, rice, and glucose.

A substitute for malt, of rather recent origin, and commercially known as “cerealine,” is prepared by subjecting hulled and coarsely ground Indian corn to the action of steam, the product being subsequently pulverised by means of hot rollers. It is said to have the following average composition:--

Water 9·98 Insoluble starch 61·43 Soluble starch, dextrine, and maltose 17·79 Albuminoids 9·07 Oil 1·22 Cellulose 0·23 Mineral matter 0·28

In addition to the foregoing, several chemical compounds, such as ammonium carbonate, tartaric acid, alkaline phosphates, boric and salicylic acids and glycerine are, or at least have been, employed as accessories in the manufacture of beer. From the investigations of the New York State Board of Health, it appears that the present adulteration of American beer--more especially of “lager beer”--is limited, so far as the brewer is concerned, to the use of various substitutes for malt, the addition of salt, and of sodium bicarbonate.

The proportion of diastase obtained by the germination of barley, or other cereals, is largely in excess of the amount required to convert into sugar the starch actually present in the grain treated; hence the brewer can add other forms of amylaceous substances, such as corn or rice, to malted barley with decided economy, and the majority of New York brewers employ such substitutes, usually in a proportion of 25 per cent. The brewer may likewise advantageously add glucose syrup to the malt infusion, since, by its use, he arrives at the same end, _i. e._ instead of obtaining all of his sugar as the result of the malting process, he directly provides himself with the same body, at least so far as it possesses value to him as a source of alcohol. The question of the sanitary effects of the use of artificial glucose as an adulterant of sugar and syrups, and as a substitute for malted grain in the manufacture of beer, has given rise to extensive controversy. In this regard, one fact seems to have been demonstrated. Glucose, as it is now to be found on the market, is free from any appreciable amount of deleterious contamination. The discovery of its artificial production has given birth to a very important branch of industry, and, according to all available reports, the commercial product at present met with is for many purposes an economical and harmless substitute for cane sugar, the chief objection to its application as such being the fact that it possesses considerably less sweetening power.

The United States National Academy of Sciences, after having carefully investigated the sanitary aspects of the glucose question, arrived at the following conclusion:[71] “That, though having at best only about two-thirds the sweetening power of cane sugar, yet starch sugar is in no way inferior to the cane sugar in healthfulness, there being no evidence before the committee that maize-starch sugar, either in its normal condition or fermented, has any deleterious effect upon the system, even when taken in large quantities.” In regard to the use of glucose as a substitute for malt in beer-making, it is asserted by some authorities that dietetic advantages to be derived from pure malt will be to some extent wanting in the extractive matters of beer manufactured partially from the artificial product. A distinction between glucose and maltose, to the advantage of the latter, is also made. The brewer, on the other hand, claims that sugar is sugar, whether obtained from the malting of grain or from the conversion of starch by the aid of acids. Regarding these bodies merely as sources of alcohol, attempts to differentiate between them are of little service. The superiority claimed for barley malt over its substitutes would rather appear to be due to its greater richness in certain soluble constituents, more especially those containing nitrogen and phosphoric acid.[72] A proposed law to prohibit the use of all malt substitutes has recently been rejected by the German Reichstag. In the English Beer Adulteration Act (1886), however, it is directed that, in case beer (ale or porter) made from other substances than hops and barley-malt is offered for sale, the fact shall be mentioned on a prominent placard, stating the nature of the foreign ingredients.

The addition of sodium bicarbonate is resorted to in order to increase the effervescing power of the beverage, and, possibly in some instances, to neutralise the acids formed by the souring of new and hastily prepared beer.[73] One of the chief objections to which certain inferior varieties of American lager beer are open is that they are not allowed to “age” properly. The apparent gain to the brewer of such beer consists in an economy of time and ice; he is also enabled to turn over his invested capital sooner than the more scrupulous manufacturer, who is thus placed in a disadvantageous position so far as trade competition is concerned. It is stated that some of the beer made in the neighbourhood of New York is sent out for consumption two weeks after its brewing.[74] Beer of this character would be apt to contain abnormally large proportions of dextrine, dextrose, etc., as well as be contaminated with unchanged yeast and other products of imperfect fermentation. It is said to be the practice to submit it to a process of clarification by means of isinglass and cream of tartar, and then impart additional life to the product by adding sodium bicarbonate, which is used in the form of cartridges or pills, and in a proportion of two ounces of the salt to the keg of beer.[75] Such a beverage obviously possesses very little claim to the name “lager” beer. It is, perhaps, to this reprehensible practice that many of the deleterious effects on the digestive organs which sometimes follow the consumption of considerable quantities of _poor grades_ of lager beer are to be ascribed; and it is often asserted to be the fact that beer drinkers who have daily drunk from 20 to 25 glasses of German beer with apparent impunity, experience disagreeable results from the habitual consumption of much smaller quantities of some varieties of American lager.

It should be remarked, in this connection, that the brewer is by no means responsible for all of the sophistications to which beer is exposed, as after it leaves his hands it may be watered by the retailer as well as allowed to deteriorate in quality by careless methods of preservation. From all procurable information, it would appear that the only questionable features of beer brewing, as now generally carried on in the United States, are the following:--

1st. The use of corn and other meals, and of artificial glucose as substitutes for malted barley.

2nd. The use of sodium bicarbonate, to impart additional life to the beer, and the occasional use of common salt.

Concerning the alleged employment of artificial bitters in beer it should be stated, that a few years since, when a very marked increase occurred in the price of hops, other bitter preparations were advertised and offered for sale in the market; unfortunately, but little authentic data can be secured in regard to the extent of their use. At present, this form of adulteration has apparently been discontinued. It is worthy of notice, that the addition of hops to beer was originally considered a falsification, and was prohibited in England by legal enactments. In regard to the manufacture and sale of partially fermented beer, the question of the prevalence of this practice must be regarded as undetermined. No objection exists to the proper use of isinglass or other forms of gelatine for the clarification of beer.

Of 476 samples of beer tested by Dr. F. E. Engelhardt, of the New York State Board of Health, about one-quarter gave evidence of the use of malt substitutes in their manufacture, but no sample was conclusively shown to be adulterated with bitters other than hops.

The examination of beer properly includes an inspection of its physical characteristics, such as taste, colour, and transparency, the determination of the specific gravity, quantitative estimations of the proportions of alcohol, carbonic acid, extractive matter, sugar, organic acids, ash and phosphoric acid, and qualitative tests for the detection of the presence of artificial substitutes for malt and hops.

When of good quality, beer exhibits a bright and transparent colour, a faint but not disagreeable aroma, and a clean and slightly bitter taste. It should be free from any signs of viscosity, the appearance of which is usually an indication of the presence of unchanged yeast.

The specific gravity of beer is determined by first removing the excess of carbonic acid by repeatedly agitating the sample in a capacious glass flask, or by pouring it from one beaker into another several times, and then filling a specific gravity bottle with the liquid and allowing it to stand at rest until all air or gas bubbles have escaped; the weight of the bottle and its contents is now taken at 15°. In order to determine the proportion of alcohol present, 100 c.c. of the beer are introduced in a suitable flask which is connected with a Liebig’s condenser and subjected to distillation until about one-half of the quantity taken has passed over. The distillate is then made up to its original volume by the addition of water, and its density ascertained by means of the specific gravity bottle, from which the percentage of alcohol present (by weight and by volume) is readily obtained upon referring to the alcoholometric table on p. 144. The frothing of beer and the volatilisation of the free acids present are best obviated by the addition of a little tannic acid and baryta-water to the sample before the distillation. An indirect method for the determination of alcohol in beer is also frequently employed. It is accomplished by first ascertaining the density of the liquor, next removing the alcohol present by evaporation over the water-bath, subsequently adding sufficient water to restore the original volume and again taking the specific gravity of the product. The density of spirit of equal strength to the beer taken (X) is obtained by the formula, D/D´ = X, in which D is the original gravity of the sample, and D´ the gravity of the de-alcoholised liquor when made up to its first volume. The following table (see p. 144) from ‘Watts’ Dictionary of Chemistry’ gives the percentages of alcohol by volume and weight, corresponding to different densities at 15°.

The amount of carbonic acid is conveniently found by introducing 100 c.c. of the _well-cooled_ beer into a rather large flask, provided with a delivery-tube which connects, first with a wash-bottle containing concentrated sulphuric acid, next with a U-tube, filled with fused calcium chloride. The latter is connected with a Liebig’s bulb containing a solution of potassium hydroxide, then with a U-tube containing solid potassium hydroxide, both of which have previously been tared. The flask is heated over a water-bath until the evolution of carbonic acid ceases, after which, the gas remaining in the apparatus is caused to traverse the potash bulb by drawing air through it. This is done by means of a tube attached to the flask and reaching below the surface of the beer. At its other extremity, it is drawn out to a fine point and connected with a small potash bulb (for the retention of atmospheric carbonic acid), by aid of a rubber tube, which permits of breaking the glass point before drawing air through the apparatus. The amount of carbonic acid present in the sample is ascertained by the increase of weight found in the larger potash bulb and U-tube.