TWELFTH ORDINARY MEETING.

ROYAL INSTITUTION, April 14, 1856.

THE REV. H. H. HIGGINS, M.A., in the Chair.

THE REV. H. H. Higgins exhibited several Jewish Coins, the shekel, however, being accounted, by the Rev. A. Fischel, modern.

Dr. Thomson read a communication on the Proceedings of the Liverpool Compass Committee.

The following paper was then read :—

ON THE ADULTERATIONS OF FOOD,

By H. SUGDEN EVANS, F.C.S., AND NEWTON SAMUELSON, F.C.S. THE attention of the public has been much directed of late to the subject of the adulteration of food, by the appearance of a series of articles in the Lancet, purporting to be the reports of a commission duly appointed to investigate the subject, and more recently, by the re-appearance of these papers in a book. The statements they contain have very naturally excited alarm, and the subject was thought of sufficient importance last year to warrant the appointment of a parliamentary committee, whose sittings are at present being held.

At all times the subject of adulterations is of great importance; but never, we think, did it assume so grave an aspect as at the present, when men, hitherto considered respectable and honourable men of business, are publicly accused of wholesale adulteration, and the public is excited, beyond measure, by the appearance of statements which we trust are overdrawn and exaggerated.

We think it behoves those in whose province the examinations of such matters come, to make known the results of their experience, either to confirm the statements alluded to, or, by contradicting them, to allay the general alarm and disgust they have engendered. With this object in view, I have, in conjunction with my friend Mr. Newton Samuelson, submitted samples of the chief articles of food to careful examination, and our results we propose to lay before the Society this evening.

It would be proper to commence the subject by a consideration of water and its contaminations, but this would furnish matter for a distinct paper, and оссиру too much time to be considered this evening in connexion with the other matters contemplated; we must, therefore,

Q

in Eng intende

and otl

mond's

he saile

well a

Brittan

and Ja

doomed

historians

that expe having a Once

drama.

few troo

been joi which t

throne By t of Pen Duke o mission the oce of Sou consid upon

ry and other operations, we have been exaggerated, and elated to produce disgust

water procurable should be Inufactures it is often found

should be present. This is and manufacture of vinegar; - Largest proportion of sulphate persistant results; arising, no doubt, time salt.

purposes may generally be drawn from amboiled is of great purity, but is sub

from the vessels it is contained in, dest spring water would be. Not long came under our notice. A sample of town was brought to me for analysis, en produced in those who had been in discovering a very decided quantity tank it was collected in on the roof of

the result, in a greater or less degree, cisterns. Hard spring waters, on the maining sulphate of potass, would exert he metal. Thus we see, that while rain vessels, is the best suited for the prein metal reservoirs it is far more liable contaminated, and in time positively

potato-farina, Indian meal, rice, rye, barley, oats, or pea and bean meal, and occasionally bone dust. The former of these are readily detected by chemical means, the latter almost entirely by the aid of the microscope.

The microscopic characters of wheat flour are clear and distinct, resting upon the shape, size, and markings of the starch grains. These are large and small bodies composing the chief bulk of the flour; the smaller grains are globular in form, and do not present any very striking characters; the large ones, however, consist of flattened round disks, convex on one side, flattened on the other; in the centre is a minute spot, around which is a series of concentric rings extending to the margin. This spot is more or less visible in all starch grains, though it is very variously shaped and placed, and the annular markings, which in wheat starch form very delicate and scarcely preceptible rings, present a very varied, yet, in each respective kind of grain, persistent appearance. These characters are modified by circumstances; disease or decay will entirely change their appearance, if not obliterate them altogether. Moisture and heat rupture the grain, and hence we may readily determine whether samples of flour have been ground from sound, diseased, or damaged corn, by the more or less distorted appearauce of the starch grains. The microscopical characters of the other starches with which wheat may be contaminated are equally distinct. [Magnified drawings of these and the other articles were exhibited.]

Besides a microscopical examination, the samples of flour were submitted to careful chemical analysis. One thousand grains of flour worked into a dough with water, were kneaded in a fine hair sieve, under a stream of cold water; we thus obtained a milky fluid passing through the sieve, and a glutinous mass remaining in it.

The milky liquid deposits starch, from which the clear supernatant liquid is decanted and boiled; a coagulum of albumen separates, which is washed, dried, and weighed; the clear liquid, separated, is evaporated to dryness in a water bath, and yields sugar and gum.

The glutinous mass left in the sieve is boiled, first in strong and then in weak alcohol; the solutions mixed and filtered while hot, give a residue of fibrine, while the hot alcoholic solution deposits caseine on cooling; the filtered solution being evaporated to a syrup, and water added, a precipitate of pure gluten is formed. Thus, by carefully collecting and drying the various deposits we can weigh them, and determine with great accuracy the proportions of bran or fibrin, caseine, gluten, starch, albumen, sugar, and salts; the amount of water being determined in the usual way, by loss at a temperature of 212°. Such a complete analysis as this is not, however, necessary or desirable

in a general way for commercial purposes; it suffices to determine the proportion of moisture, starch, gluten, and sugar, as well also as the mineral salts which may have been added for purposes hereinafter to be described.

These salts may be determined in the following manner, with sufficient accuracy:—a proportion of suspected flour is triturated in a sieve with water, as above described, the milky fluid being collected in a conical shaped glass: when the starch has thoroughly subsided the clear liquor is decanted off, boiled and filtered; to one portion hydrochloric acid and ammonia are carefully added, when, if alum be present, a more or less copious gelatinous precipitate will be produced: this is alumina. To the other portion chloride of barium is added, when a white precipitate will be formed if sulphuric acid be present; and these two re-actions are conclusive evidence of the presence of alum, the quantity being calculated from the weight of aluminous preparation obtained from the whole quantity of liquor.

The starchy deposit is dried in its conical glass, from which it is then readily removed. The tip of the cone, which of course will contain all the denser matters, is removed and digested in cold water; the clear liquor is filtered off, and tested with chloride of barium and oxalate of ammonia; white precipitates with these re-agents clearly prove the presence of sulphate of lime, or gypsum. The residue left after digesting the deposit in water is treated with hydrochloric acid; effervescence indicates the presence of chalk, which must be confirmed by the addition of oxalate of ammonia to the filtered solution, which will give a precipitate if lime be present.

Besides these tests a portion of the flour must be boiled in water slightly acidulated with hydrochloric acid; or, what is better, burn and calcine the ash of a portion of the flour, and treat it with dilute acid, filter, and add acetate of potass with a few drops sesqui-chloride of iron; if bones have been mixed with the flour, a copious white precipitate of phosphate of iron is produced.

Various chemical tests have been proposed for detecting admixtures of other farinaceous substances with bread and flour, but having found that the microscope furnishes the readiest and more certain results, we have deemed it sufficient to confine ourselves to its indications.

Having submitted many samples of flour in this way to examination, we have found that, as a rule, the public are supplied with a genuine article, although an occasional exception has come under our notice. Thus, we remember some time ago examining a sample of flour which had evidently been prepared from, or largely admixed with, damaged wheat, as a vast proportion of the starch grains were ruptured, and

more or less collapsed, while a large quantity of alumina was found, arising from the addition of alum, made no doubt for the purpose of overcoming the damaged wheat, and making the flour bake as well and as white as the best. Another sample of French flour, of great weight, was found to contain a very considerable quantity of gypsum; while in a third the characteristic starch grains of pea meal, and a little bone dust were brought to light.*

With these few exceptions we have found flour to be genuine; but in all, more or less of alumina was detected; which we think arises from the addition of small portions of alum in the process of grinding, and we certainly are not prepared to say that this slight addition is capable of exerting any injurious effect upon health; for our experiments go to establish the theory proposed by Liebig, that during the process of baking the alum is destroyed: but of this we shall have to speak more fully in reference to the next article of food which claims our attention, namely bread.

BREAD, emphatically termed the staff of life, has long been looked upon with suspicion, and many are the laws and regulations which have from time to time been formed for the protection of the public against fraud in this most important and necessary article of diet; yet how defective these laws are, and how easy it is to evade their power and intention is daily proved by the amount of alumina found in the bread as supplied to the public, and the rapidity with which a loaf loses weight by keeping.

We have not found that other grain than wheat is employed in the manufacture of bread in this part of the country,+ but we do find that substances are mixed with the flour, which cause it to retain a larger proportion of water, and cause a damaged or inferior flour to produce as saleable a bread as the best. Mitchell tells us that it is a universal custom in England to mix boiled potatoes with the dough; such an addition would of course greatly increase the weight of bread produced, but diminish its nutritive properties at least twenty per cent. We scarcely feel prepared wholly to contradict this statement, but in numerous samples of bread we have examined, we have failed to discover any appreciable quantity of potato starch, or the starch granules of any other grain, and our samples have been drawn from all sources, though confined to white bread.

But for the purpose of increasing the weight of the bread, and of

Since reading this paper Mr. Evans has examined two samples of flour, which contained large quantities of the sporules of the uredo fungus, that produces the smut in wheat, and in one they existed to a most injurious extent.

+ Since this was in type we have discovered a pretty uniform admixture of Maize or Indian Corn Flour in the bread of one of our most esteemed bakers.-H. S. E.