EXTRACTS FOREIGN AND DOMESTIC. 361 



)N THE FORMATION OR SECRETION OF CARBON BY 

 ANIMALS.* 



BT MR. ROBERT RIGG. 



The scientific world is at present much occupied with the appli- 

 ation of chemistry to animal and vegetable physiology ; and it 

 aay be interesting to some of your readers to know, that by a few 

 ery simple experiments they may satisfy themselves upon that 

 ranch of the subject which relates to the formation of carbon by 

 nimals. 



Suppose an animal, which comprises in its whole system 50 

 larts by weight of carbon, to be kept for five days, during which 

 t consumes other 50 parts, it is evident that if during the five days 

 t gives to the atmosphere 60 parts, and at the end of that time it 

 5 found to have increased its weight of carbon by 10 parts, there 

 5 a positive gain of carbon equivalent to 20 per cent. 

 : The experiment may easily be made upon young small animals, 

 ^ake two of these so nearly alike that there can be no material 

 iflFerence in the weight of the carbon they comprise. Kill one of 

 liese, and expose it to a temperature not exceeding 220°, for two 

 r three days; it may then be powdered, and by subjecting an 

 iverage sample to analysis with oxide of copper, the weight 

 |f carbon comprised in the entire animal may be determined 

 !rith the greatest certainty. The other being supplied with food, 

 tie weight and chemical constitution of which is ascertained, should 

 e kept in a limited atmosphere, which must be tested and changed 

 very one, two, or three hours,f the increased proportion of car- 

 onic acid of that atmosphere will show the quantity of carbon 

 liven off by the animal in the course of the experiment ; and the 

 icrease or decrease of carbon in the animal itself may be ascer- 

 iined in the manner above mentioned. 



In this manner I have experimented upon many animals ; and 

 dthout taking account of the carbon which passes off otherwise 

 lan by respiration, the result has invariably been a great increase 

 jf carbon — an increase which cannot be accounted for, unless we 

 jonclude that carbon is secreted by animals. 



Amongst my best experiments, are those made with young mice. 

 . healthy young mouse, weighing 200 grains, comprises in its 

 pnstitution from 25 to 30 grains of carbon ; when fed daily with 

 grains of bread moistened with water, containing about 16 



rains of carbon, it increases in weight, and imparts to the atmos- 



here from 20 to 26 grains of carbon, the quantity varying gene- 



• Medical Gazette, Aug. 23, 1844. 



t The health of animals appears to be affected by aa atmosphere eontaining more 

 an 5 per cent, of its volume of carbonic acid. 

 VOL. I. NO. II, M 



