DOMESTIC AXniALS. 265 



We here perceive a large loss of water, carbon, hydrogen, 

 &c. Nearly all this loss of carbon and hydrogen, escaped by 

 respiration, while most of the water, oxygen, nitrogen and 

 salts, passed off in perspiration. In further illustration of the 

 subject of respiration, Liebig says, "from the accurate de- 

 termination of the quantity of carbon daily taken into the 

 system in the food, as well as of that proportion of it which 

 passes out of the body in the fceces and urine, unhurried^ that 

 is, in some form uncombined with oxygen, it appears that ail 

 adult taking moderate exercise, consumes 13.9 oz. of carbon 

 daily." The foregoing are facts in the animal economy, ca- 

 pable of vast practical bearing in the management of our 

 domestic animals. But before following out these principles 

 to their application, let us briefly examine 



THE EFFECTS OF RESPIRATION. 



We have seen from the experiment of Boussingault, that 

 there is a loss of 6 Ibs. 6 oz. of carbon, and 8 oz. of hydrogen 

 in the food of the horse, and something less in that of the 

 cow, every '24 hours, which has not been left in the system, 

 nor has it escaped by the evacuations. What has become of 

 so large an amount of solid matter ? It has escaped through 

 the lungs and been converted into air. The carbon and 

 hydrogen of the food have undergone those various trans- 

 formations which are peculiar to the animal economy, diges- 

 tion, assimilation, &c., which it is not necessary, nor will 

 our limits permit us here to explain ; and they appear at last 

 in the veinous blood, which in the course of its circulation, is 

 brought into the cells of the lun<js. The air inhaled, is sent 

 through every part of their innumerable meshes, and is there 

 separated from the blood, only by the delicate tissues or mem- 

 branes which enclose it. A portion of the carbon and hydro- 

 gen escape from the blood into the air-ceils, and at the instant 

 of their contact with the air, they effect a chemical union 

 with its oxygen, forming carbonic acid and the vapor of 

 water, which is then expired, and a fresh supply of oxygen 

 is inhaled. This operation is again repeated, through every 

 successive moment of animal existence. Besides other pur- 

 poses which it is probably designed to subserve, but which 

 have hitherto eluded the keenest research of chemical physi- 

 ology, one obvious result of it is, the elevation of the tempra- 

 ture of the animal system. By the ever-operating laws of 

 nature; this chemical union of two bodies in the formation of 

 a third, disengages latent heat, which taking place in contact 

 JL 



