that the results so obtained give no indication of the commercial value of the extract.

The following additional methods were used in this investigation :—

Acidity.—Titrate a solution of 0·5 gram in 800 c.c. of water with deci-normal potassium-hydrate, using phenolphthalein as indicator; the result is then calculated and expressed in terms of acidity as lactic acid.

Insoluble and Coaguable Proteids.—For these determinations the provisional methods of the Association of Official Agricultural Chemists for meatfibre and coaguable proteids were used.^*

Proteoses were determined by the zinc-sulphate method.^†

Peptone-like bodies and polypeptides were precipitated together with the proteoses by the tannin-salt reagent, the amount of peptone-like bodies and polypeptides being found by difference.^‡

Total Meat Bases.—From the nitrogen found in the tannin-salt filtrate deduct the nitrogen found as ammonia, the difference being the nitrogen as meat bases.

Ammonia was determined by the magnesium-oxide method.^§

Purin bases were determined by Schittenhelm's method.^∥

Kreatin and kreatinin were determined by Follin's colorimetric method.^¶

Phosphoric acid and potash were estimated in the residue from the ashdetermination.^*

The following table shows the composition of the extract examined.—

The following table shows the composition of the mineral salts of the extract examined :—

The moisture-content as laid down by Liebig should not exceed 21 per cent. The total mineral salts, according to the same authority, should vary from 15 to 25 per cent. The mineral salts found in true meat-extracts are potassium-dihydrogen-phosphate, potassium-monohydrogen-phosphate, and the sulphates of calcium, potassium, and sodium, and the chlorides of sodium and potassium. Chloride of sodium is a minor constituent of meat-extract, the chlorine being present almost entirely as the potassium-salt. Salt is sometimes added to extract of meat in order, it is stated, to preserve the product, but the fact that it increases the profit is probably the greater incentive to its use.

In the extracts examined under the chemical control of this laboratory no added salt is found, and experience shows that non-salted extracts keep quite as well as those to which large amounts have been added. Since added salt is not necessary to keep extracts from decomposition, the addition of such can only be regarded as an adulteration.

Konig^* states that the mineral salts, especially the potassium-salts, present in the meat-extract are valuable on account of their action on the nervous system.

Chittenden^† finds that the content of potash-salts causes a quicker and stronger heart-beat.

The acidity of meat-extract, determined by using phenolphthalein as indicator, is calculated to lactic acid as a matter of convenience, and for the sake of comparison with other investigators.

It is recognized that the acidity of meat-extract is due to various constituents, but sarcolactic acid is the predominating acid. It has been suggested that a part of the acidity is due to the phosphates present, but it is probable that the principal salt of phosphoric acid is the secondary potassium compound, which is neutral to phenolphthalein.^‡

Fat is a detrimental ingredient in a meat-extract, and if present in large amounts indicates an imperfect method of manufacture, and affects the keeping-quality of the extract.

The total nitrogen in meat-extract varies from 6 to 9 per cent. However, in judging the value of an extract it is of importance to consider the forms in which the nitrogen exists rather than its total amount: it has been found by Chittenden^* that while the nitrogen-content is high it is not available for the body's use as a food.

Insoluble proteids should not be present in large amounts: their presence in quantity indicates either the addition of meat-fibre or imperfect methods of manufacture. To add meat-fibre or other pretein to a meat-extract only reduces the proportion of meat bases to which the extract owes much of its true value, and merely adds small amounts of nutriment at an unreasonable price.

Coaguable proteids are also found in small amounts in all meat-extracts. It is impracticable to prepare a meat-extract containing more than a very small amount of coaguable proteids, for the reason that in the process of evaporation the temperature necessary coagulates the proteid.

Proteoses include the albumoses and certain gelatinoids. Most of the nitrogen attributed to proteoses in meat-extract is due to gelatin or gelatoses, and, as these bodies have a very low nutritive value,^† it is apparent that the claim of a high nutritive value for meat-extract rests upon very unconvincing evidence. It is certainly incorrect to suppose that because proteoses are present there must be considerable nutrient property in meat-extract.

Peptone-like bodies and polypeptides so described in this paper correspond with the nitrogen usually determined as and attributed to peptones, but, as the filtrate from the zinc-sulphate precipitate furnished negative results when submitted to the biuret test, it is apparent that no natural peptones are present in the meat-extracts examined. Other investigators have reported a similar experience, and for that reason the absence of peptones in meat-extracts has met with a more or less general acceptance.

While natural peptones are excluded, it is probable that the nitrogen found in this determination is largely due to the non-biuret-reacting polypeptides of Fischer,^‡ these substances being intermediate between the peptones and amido acids.

Fischer has pointed out that the commercial product is very closely related to the natural peptones, and that peptones are essentially a mixture of polypeptides, and he has further pointed out^§ that many of the polypeptides fail to give the biuret reaction.

As no true peptones are found in most meat-extracts, it is seen that the claims made concerning the nutrient value of meat-extracts on account of the presence of peptones cannot be substantiated.

It is to the mineral salts and meat bases that a meat-extract owes its true value. The mineral salts have already been discussed, but it is the meat bases that give meat-extracts their chief value. Their chemistry is most complex; physiologically the most important are kreatin and kreatinin, and the purin bases. The purin bases usually found are xanthin, hypoxanthin, adenin, and guanin. A considerable number of other meat

bases have been isolated from meat-extract in recent years—namely, ignotin, oblitin, methylguanidin, carnomuscarin, neosin, novain, alanin, leucin, and glycocoll;^* these are present in extremely small quantities, and it is impossible with our present knowledge to determine all of the meat bases in meat-extracts.

The meat bases are the products of the breaking-down of proteins in the vital processes of the body, and are excreted for the most part unchanged, and have little use as tissue-builders; neither do they produce heat or energy; they are therefore not foods.

Recent experiments^† show that meat bases furnish relief to fatigued muscle, and are powerful exciters of gastric secretion. They are thus most valuable, in that they create an appetite and prepare the system for food and aid its digestion. The custom of preceding a meal with soup which contains these bases has therefore a strong physiological warranty.

Ammonia when in quantity indicates some degree of putrefaction. Probably some of the ammonia present is in combination with acids of the fatty series.

Recently preparations made from yeast have been placed on the market as substitutes for and adulterants of meat-extracts. While as far as the taste and appearance are concerned they resemble meat-extracts, they show marked chemical differences, and are in no sense true substitutes, since they lack the valuable constituents and stimulating properties of meat-extracts, and their salts and bases.

Yeast on hydrolysis yields extractives somewhat similar to those obtained from meat, and when evaporated by the open-pan process darkens and looks like extract of meat. Caramel is sometimes added to darken the colour.

The following is the analysis of a sample of this class of product sold in this country :—

As in the case of the meat-extracts examined, no natural peptones were found.