THE CHEMISTRY OF COOKERY. 221 



— that is, by the use of tea. And, if the waste be lessened, the neces- 

 sity for food to repair it will be lessened in an equal proportion. In 

 other words, by the consumption of a certain quantity of tea, the 

 health and strength of the body will be maintained in an equal degree 

 upon a smaller quantity of ordinary food. Tea, therefore, saves food 

 — stands to a certain extent in the place of food — while, at the same 

 time, it soothes the body and enlivens the mind." 



He proceeds to say that " in the old and infirm it serves also an- 

 other purpose. In the life of most persons a period arrives when the 

 stomach no longer digests enough of the ordinary elements of food to 

 make up for the natural daily waste of the bodily substance. The 

 size and weight of the body, therefore, begin to diminish more or less 

 perceptibly. At this period tea comes in as a medicine to arrest the 

 waste, to keep the body from falling away so fast, and thus to enable 

 the less energetic powers of digestion still to supply as much as is 

 needed to repair the wear and tear of the solid tissues." No wonder, 

 therefore, says he, "that the aged female, who has barely enough in- 

 come to buy what are called the common necessaries of life, should 

 yet spend a portion of her small gains in purchasing her ounce of tea. 

 She can live quite as well on less common food when she takes her tea 

 along with it ; while she feels lighter at the same time, more cheerful, 

 and fitter for her work, because of the indulgence." 



All this is based upon the researches of Lehmann and others, who 

 measured the work of the vital furnace by the quantity of ashes pro- 

 duced — the urea and phosphoric acid excreted. But there is also 

 another method of measuring the same, that of collecting the expired 

 breath and determining the quantity of carbonic acid given off by 

 combustion. This method is imperfect, inasmuch as it only measures 

 a portion of the carbonic acid which is given off. The skin is also a 

 respiratory organ, co-operating with the lungs in evolving carbonic 

 acid. 



Dr. Edward Smith adopted this method of measuring the respired 

 carbonic acid. His results were first published in " The Philosophical 

 Transactions " of 1859, and again in Chapter XXXV of his volume 

 on "Food," "International Scientific Series." 



After stating, in the latter, the details of the experiments, which 

 include depth of respiration as well as amount of carbonic acid re- 

 spired, he says : " Hence it was proved beyond all doubt that tea is a 

 most powerful respiratory excitant. As it causes an evolution of car- 

 bon greatly beyond that which it supplies, it follows that it must 

 powerfully promote those vital changes in food which ultimately pro- 

 duce the carbonic acid to be evolved. Instead, therefore, of supplying 

 nutritive matter, it causes the assimilation and transformation of other 

 foods." 



Now, note the following practical conclusions, which I quote in 

 Dr. Smith's own words, but take the liberty of rendering in italics those 



