236 



naturalist, Man can live very well upon air; nay, in point of fact, he 

 does live on air alone, and nothing else whatever : and it is his busi- 

 ness, aided by chemistry, to make good the assertion. 



The Guacho of the Pampas consumes daily ten or twelve pounds 

 of meat; the word bread does not exist in his vocabulary : the Irish- 

 man regales himself on " potatoes and point :" the hunter of the 

 prairies roasts the hump of the buffalo he has brought down with his 

 bullet: the Chinese enjoys his fattened rats and delicate puppies : 

 the Greenlander in his snow- hut consumes with the greatest gusto his 

 whale fat : the negro-slave sucks his sugar-cane and fattens upon the 

 farinaceous banana : the oriental merchant, when setting out on a 

 journey, fills his bag with sweet dates : and the Siamese crams him- 

 self with rice : "wheresoever over the whole inhabited earth we ap- 

 proach and demand hospitality, in almost every little spot a different 

 kind of food is set before us, and the ' daily bread ' offered in another 

 form ;" and these so varied kinds of nourishment contain a few simi- 

 lar matters, which peculiarly serve for the food of man, whence the 

 unity of the end produced from the multiplicity of materials. 



Four elementary substances, out of the fifty-three or thereabouts, 

 which have been discovered in the numerous substances by which 

 we are surrounded, alone take an essential share in the composition 

 of all that is termed organic or living existence : these four are oxy- 

 gen, hydrogen, carbon and nitrogen; and these form all the substances 

 of which plants and animals are composed. 



" The four elements under consideration form numerous compounds 

 by their union one with another; but only two classes of these have 

 a very deep importance in relation to the organic world. One of the 

 classes comprehends the substances which are compounded of all four 

 elements. This includes albumen, fibrine, caseine and gelatine. All 

 animal bodies are formed out of these substances, which, when sepa- 

 rated from them as dead matter, all pass rapidly by decomposition 

 into w T ater, ammonia and carbonic acid, which are diffused through 

 the air. The second class, on the other hand, includes the substances 

 devoid of nitrogen, namely, gum, sugar, starch, the liquors prepared 

 from them, such as spirit, wine, beer, and, lastly, all the various kinds 

 of fat. All these merely pass through the animal body, since the car- 

 bon and hydrogen are burnt off by means of the oxygen received in 

 respiration, and are expired as carbonic acid and water. By this 

 slow but uninterrupted process of combustion is maintained the heat 

 indispensable to life. But by the recent brilliant discoveries in che- 

 mistry and physiology we have become aware that the animal body is 



