the contrary, contain the other elements that are in protein but do not have the sulfur element. They belong to that class of bodies which is known as simple amido compounds. All of these bodies are mixed together in meat juice or beef extract, and it is an important task of the chemist to separate them, both from an analytical point of view and the determination of their relative abundance. There is also another soluble or semisoluble protein substance in these extracts derived from the tendinous tissues and bones, namely, the gelatine or glue. This is quite a common product, being the soluble protein procured by the digestion of the tendons and bones. It is important, therefore, that the chemist should distinguish between the gelatine and the amido bodies. There is also a true and a false protein form of these soluble bodies, the true one being formed by natural proteolytic ferments and the false one being formed by heat or digestion under pressure of steam. The chemist should also be able to distinguish between the true extract formed directly from the meat and the yeast extract used as an adulteration.
It is not the purpose of this manual to enter into the details of how these different bodies may be distinguished from one another, as that is purely a chemical study. It is due, however, to the general reader that some explanation be given of the different classes of bodies which are contained in these extracts.
Relation between the Price of an Extract and its Nutritive Value.—The studies made in the Bureau of Chemistry show that there is little relation between the price of a beef extract and its real nutritive value. In three cases of extract which are all well known brands and are of the thick or pasty variety, showing that a dissolved meat had been added to them, the average weight of a package costing 45 cents was only 55 grams, or nearly a cent a gram. In another three samples of extract, also well known brands, of the same pasty variety and costing little more per package, it was found that the weight of the more expensive variety was double that of the first, costing only one-half cent per gram. In the case of the liquid extracts where no pasty material is incorporated there is still greater variation in the relation of the price to the nutritive constituents. An extract which retails for one dollar per bottle contains 91.69 percent of water and only .42 percent of nitrogen. Another so-called meat extract which retails at 60 cents per bottle must have been wholly an artificial product, since it contained no creatin or creatinin at all. It was also preserved by the addition of alcohol and contained an artificial coloring matter.
The ash existing in these extracts is, of course, usually due to the presence of large quantities of common salt. Sodium chlorid is added to this extract without any definite rule at all and sometimes in very excessive quantities. In some cases thirty percent of the total extract is composed of common salt. In other words, a person taking a solution of this kind would be injecting into his stomach a very concentrated brine. When common salt may
