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taining a large amount of a fat known as cacao butter. To prepare cocoa for table, it is necessary that the amount of this fat should be reduced. This is attained by using one of two methods, viz.: (1) The roasted and ground cocoa is mixed with starch and sugar so as to dilute its richness; (2) before grinding the cocoa, it is heated and pressed, whereby a considerable amount (generally nearly one-half) of its natural fat is squeezed out. This latter method is decidedly the more desirable one, because not only is the fat removed, but all the other nourishing and stimulating principles are at the same time concentrated. A typical cocoa of English manufacture by this process is found in the wellknown Cadbury's cocoa essence. This article has always been, in our experience, exceedingly constant in its nature, and the last time we analysed it we found:

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Here then is what constitutes, in our opinion, a specimen of a properly-prepared cocoa, nothing added to dilute its flesh-forming or stimulating properties, and nothing deducted except the indigestible fat. There are, of course, other excellent prepared cocoas in the market, but we have purposely chosen Cadbury's as the type to illustrate these remarks because it is really the standard English article, and was, we believe, the first so manufactured. Indeed, until it was brought out, the only style of cocoas known to English consumers were compounds that produced, when cooked, what was practically little more than sweetened starch flavoured with real cocoa. Even now persons are to be found who prefer such articles, or who simply drink what their grocers send them and call it cocoa. If our correspondent happens to be one of these, let him try the real article, prepared by the fat extraction method, and give up buying extra starch and sugar under the name of prepared cocoa. To give a still more striking confirmation of our remarks let our readers glance at the following average amounts of flesh-forming ingredients present in the substances named :

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EXALGIN may be distinguished by the following simple test from acetanilid and phenacetin: 1 gram. is dissolved in 2 c.c. chloroform (acetanilid requires 6 c.c. and phenacetin 20 c.c. chloroform) and 20 c.c. petroleum ether (sp. gr. 0·650) added; the solution should remain clear. 10 per cent. phenacetin and 20 per cent. acetanilid can be detected by the formation of a precipitate after standing a short time.-(E. Hirschsohn).

A TEST FOR HYDROGEN DIOXIDE.-The solution to be tested is made alkaline, and then a soluble neutral salt of lead or copper added ; a deep brown-red precipitate, rapidly changing to red, and finally to white, indicates hydrogen peroxide. In concentrated solutions effervescence is also to be observed. Ozone solution (Lender's) does not give this test.-(A. O. Gawalowski.)-Am. Journ. Pharm.

THE

ANALYST.

JULY, 1890.

CONTENTS.

PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS

(a) REPORT OF MEETING

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(b) REMARKS ON THE BITTER OF HOPS AS DISTINGUISHED FROM THE BITTER OF QUASSIA

AND OTHER HOP SUBSTITUTES-BY MATTHEW A. ADAMS

(c) DISCUSSION ON MR. ADAMS' PAPER:

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Owing to the pressure of the Society's matter this issue of the ANALYST is entirely devoted to the same.

PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS.

An ordinary meeting was held at Burlington House on Wednesday, the 11th ult., the President, Mr. Adams, in the chair.

The minutes of the previous meeting were read and confirmed.

The following gentlemen were elected as members:-S. J. Steel, F.C.S., Blackheath, as Associate; T. H. Pearmain, Assistant to Mr. Allen.

The following gentlemen were proposed for election as members :-G. A. Milne, F.C.S., Analytical Chemist, Norton Malton; H. Barclay, Analytical Chemist, Workington; Edgar Richards, of the American Inland Revenue Department.

The following papers were read and discussed :

"On Dyed Sugar."-By C. E. CASSAL.

"On some Recent Advances in our Knowledge of the Sugar Group."-By Dr. W. J. SYKES.

"On some Points in the Analysis of Milk."-By H. DROOP RICHMOND.

"Notes on the Chemistry and Detection of certain Hop Substitutes.”—By A. H.

ALLEN.

The country meeting of the Society will be held at Gloucester on the 25th inst. Full particulars will be duly announced.

REMARKS ON THE BITTER OF HOPS AS DISTINGUISHED FROM THE
BITTER OF QUASSIA AND OTHER "HOP SUBSTITUTES."
BY MATHEW A. ADAMS.

Read at Meeting, May, 1890.

It was at the commencement of 1875 that a consideration of the bitter principle of the hop was first brought under my notice with a view to distinguish it by chemical or physical means from the bitter of quassia or other substitutes of a similar nature, reputed to be used in the composition of sundry proprietary articles variously called "Hop Substitutes," "Hop Supplements," "Bavarian Hop Bitter," and so on, which articles

were extensively advertised, and said to be largely used to replace the true hop bitter in the brewing of beer.

The "Hop Growers' Association," as it was called, applied to me for advice and assistance in the endeavour to discover some means for distinguishing, by chemical analysis or otherwise, between these substances. Positively nothing appeared then to be known concerning these bitters, and being unable myself to supply any information, upon my advice, certain prominent chemists who had made the question of food analysis a special study were consulted, but without any satisfactory result.

In September, 1875, the Association offered a reward by advertisement in various professional papers of £100 for the discovery of a method for detecting the presence of quassia or other substitutes for hops in malt liquor. This offer, if I remember right, was to hold good for twelve months. Two others and myself were appointed to test and adjudicate upon the methods of any claimants for the reward, but no claim was made and not a scrap of information obtained. So the offer of a reward lapsed, and the whole proceeding was reckoned a failure.

Meantime I had been turning the thing over in my mind, and was invited to undertake the investigation myself, and a small sum was set apart as remuneration to me for doing so.

I was supplied with samples of the various hop substitutes then in the market. I obtained samples of various medicinal tonic bitters which appeared to enter into the composition of the hop substitutes, and worked at the thing myself with the result that, early in 1877 I was able to write to the Chairman of the Hop Growers' Association announcing my ability to detect foreign bitters in beer, and offering to subject myself to a trial. Twenty-seven samples were sent me to test my ability to do so, some of them had been specially prepared by the committee, and my analysis showed that nine had been bittered with foreign bitters and eighteen were not so bittered, and this was correct. The eighteen pure samples were mostly of porter from various parts of London. The Association were very much disappointed that quassia had not been discovered in any of these London beers, and they then proposed to undertake a roving expedition throughout England to find a beer with foreign bitter in it. I had no objection to that, but could not see the fun of doing all this work without being paid for it, and offered to disclose the secret of my process for the lapsed reward, or to do any number of analyses at a fixed fee. This they did not consent to, but put themselves into communication with some other chemist, but who that chemist was I never enquired and never knew. That was the end of my dealings with the Hop Growers' Association, and the subject of hop bitters, so far as I was concerned, was put altogether on one side, and no one, I imagine, will blame me for not being in a temper to publicly disclose the results of my researches for the benefit of a rival by whom I had been supplanted. In 1887, as you all know, Mr. Allen invited communication on this subject from members of this Society, and at the May meeting, which was well attended and wholly given up to a consideration of the matter, Mr. Allen read a very interesting paper on the subject, and many others, either by letters or voice, also contributed to the discussion that followed. The part that I took was to testify to the practicability of distinguishing between the hop and hop substitutes, which I did by private com

munication with Mr. Allen before he read his paper, and also subsequently at the public meeting. In February, 1888, Mr. Allen again brought the subject forward for discussion, and I explained my method, so far as the use of sulphuric acid is concerned, and subsequent to this in a foot-note on page 46 of the ANALYST, Mr. Allen reports that he had succeeded with the sulphuric acid treatment on the sample of hops, which gave the sensible bitter extract (by the ordinary method of applying the lead test), and found all trace of bitter had disappeared, even when the concentrated solution was agitated with chloroform and the evaporated chloroform solution tasted.

It is not that I am over concerned to identify myself as the original investigator in the field that I have ventured to occupy a few minutes with this historical statement. My object is to repel an insinuation that I had unaccountably kept secret my knowledge on this subject. For the credit of our Society I take leave to say that there is no more liberal-minded body of men to be found than the members of this Society. I have never known an instance where information has been withheld for private interest or refused by one member to another when applied for. The value of this freemasonry among us is incalculable; but for this the public analysts of Great Britain could not have been the competent men they now are. Aye, nor would the present knowledge of food analysis be what it now is; and in passing I should like to say it has often occurred to me that the strongest argument to be found against the fusion of this Society with any other is the possible risk that to some extent the opportunity for this freedom of interchange of thought and experience within the limits of our special field might be jeopardised. Since the February meeting in 1888, the subject again fell into abeyance, and it was only a week or two ago that Mr. Robert Norton, the member for the Tonbridge division of Kent, called upon me to ask whether I could furnish any information on the chemical aspect of the question for the Select Commission of the House of Commons now enquiring into the causes of the depression in the hop industry. I consented to do so, and did give evidence on May 1st, and now ask your kind attention to a few hastily put together remarks on the subject.

Anyone by the unaided sense of taste may observe a wide difference between various bitters in the duration of their effect upon the palate, and this is a characteristic that seems to divide bitter substances, sharply, into two categories :—

1.-Fixed Bitters.

2.-Fugitive Bitters.

These characteristics manifest themselves

1.-Physiologically in their effect upon the body, and also

2. Chemically in their behaviour under chemical treatment.

A fixed bitter affects the organ of taste in a way that is enduring, and not only does the effect of the bitter last a long time, but also for the time being it appears to overwhelm the taste organs; so that these taste organs require a considerable time to recover their entire freedom to repeat their office. On the other hand a fugitive bitter has not anything like so penetrating an effect, and the effect lasts but a comparatively short time, leaving the palate clean and free to appreciate other flavours. Moreover, one can, as it were, taste through the bitter of the fugitive bitter, whereas the fixed

bitter covers everything, and, so to speak, monopolises the sense of taste, hangs about the mouth, and perverts other flavours for a long time.

In short, the stimulus to the gustatory fibres of the glossopharyngeal nerve, is in the one case transitory, but in the other long continuing, for which we shall, I think, presently find an explanation. The hop bitter will serve as an example of what I call a fugitive bitter and quassia of a fixed bitter. It is not only from a physiological, but in some respects also from a chemical point of view, that this characteristic distinction is displayed.

Quassia and its allies will stand a deal more rough usage, so to speak, and yet survive, whilst the hop bitter is destroyed; in a word the one is a much more stable compound than the other, but I take the liberty of applying the terms "fixed" and "fugitive" in a chemical sense, simply because by certain methods of chemical treatment, presently to be described, the fugitive is driven away whilst the fixed is left

behind.

The proximate nature of the hop bitter is ascribed to several resins varying in intensity of bitter, but I hardly think its true nature has yet been positively and definitely made out. I suspect that a part, if not the whole, of this bitter is of the nature of a glucoside; at all events, this view fits in very well with the facts. For instance, fermentation removes a large part of the bitter, and boiling a 2 per cent. decoction of hop with 21 per cent. of sulphuric acid under a reflux condenser for two or three hours every trace of bitter is entirely removed. But quassia and its allies are not at all affected by this treatment. This is the key note of the distinction between the fixed and fugitive bitters-the latter being more or less of the nature of the glucosides, on this account disappearing by conversion into glucose in the acidified decoction, and in the mouth by digestion through the agency of the ferment proper to the saliva-and so we can now understand how it is that the palate when dealing with a fugitive bitter clears up so quickly, while, on the other hand, a fixed bitter, being insusceptible of fermentive change maintains its bitter effect so long.

As regards the argument that the fugitive character of the taste of hop bitter is due to its glucoside nature, allow me to draw your attention to the fact that salicin, a very bitter substance, but also a well-known glucoside, has this same fugitive characteristic in respect of taste, for when a saturated solution is placed on the tongue all bitterness soon vanishes.

The hop bitter, however, though it is of the nature of a glucoside, is by no means easy of conversion, so that prolonged boiling with the sulphuric acid is necessary, and fearing that this somewhat severe treatment might possibly, to a certain extent, attack some of the fixed bitters, it seems as well to take advantage of the selective power of the basic acetate of lead to assist and hasten the removal of the bitter, so that the process I employ is as follows::

FIRST PROCESS.

The decoction is made to boil, and basic acid of lead solution is added until the point of saturation is just reached. The boiling is continued for some time, after which the precipitate is filtered off, and the filtrate at once treated with sulphuric acid until there is a decided excess. The lead sulphate is filtered off, and the clear acid

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