22 Professor Liebig on the 



bean of the Phaseolus vulgaris, according to the same chemist, 

 contains 0'70of fat soluble in aether. Fresenius obtained from 

 peas 2*1 per cent, of a substance soluble in aether, from linseed 

 1*3 per cent. 



For every 1000 lbs. of peas or beans the organism receives, 

 according to Braconnot 12 lbs., according to Fresenius 21 lbs. 

 of fat, and from as many beans only 7 lbs. of fat. 



Beer, as far as I am aware of, contains no fat : Fresenius 

 obtained from the pulp of the beet-root 0*67 per cent, of a 

 substance soluble in aether. 



According to further direct examinations made in our 

 laboratory, 1000 parts of dried potatoes gave 3*05 parts of a 

 substance soluble in aether. This substance possessed all the 

 properties of resin or wax; we will, however, assume that 

 potatoes contain y^jo" of their weight of fat. Three one-year- 

 old pigs, fattened with 1000 lbs. peas and 6825 lbs. potatoes 

 fresh boiled, which are equal to 1638 lbs. of dried potatoes, 

 increased in weight in thirteen weeks from 80 lbs. to 90 lbs. 

 each. A fully fattened pig averages in weight from 160 lbs. 

 to 170 lbs., and after killing the fat weighs from 50 lbs. to 

 55 lbs. The three pigs have consumed 21 lbs. of fat, con- 

 tained in the 1000 lbs. peas, and 6 lbs. in the 1638 lbs. of po- 

 tatoes, together therefore 27 lbs. Their bodies, however, con- 

 tained from 150 lbs. to 165 lbs. of fat. There is an increase of 

 from 123 lbs. to 135 lbs. more fat than the food contained. A 

 pig one year old weighs from 75 lbs. to 80 lbs. ; suppose it to 

 contain 18 lbs. of fat, there still remains, leaving entirely out 

 of question the matters soluble in aether contained in the ex- 

 crements, 69 lbs. to 74 lbs. of fat* ; the production of which 

 in the organization cannot be doubted, and whose formation 

 remains to be accounted for. 



M. Boussingault's examinations concerning the influence 

 of food on the quantity and composition of the milk of the 

 cow, furnish other more important grounds for the opinion 

 that animals produce fat out of certain food, which is neither 



* M. Vogt, a butcher at Giessen, in answer to some questions of mine, 

 gave me the following as the result of his experience, which has been con- 

 firmed by other intelligent persons: — A restless pig is not adapted for fat- 

 tening, and however great the supply of food it will not grow fat. Pigs 

 which are fit for fattening must be of a quiet nature ; after eating they must 

 sleep, and after sleeping must be ready to eat again. When a pig is a year 

 old it weighs from 75 lbs. to 80 lbs., and if the fat is intended to be used as 

 lard, it must be fed daily for thirteen weeks with 20 lbs. to 25 lbs. of boiled 

 potatoes, and about a measure of peas (2 litr.); towards the end of the 

 time the food may be somewhat diminished. A pig so fattened weighs 

 from lb'OIbs. to 170 lbs., and contains of fat and lard, taken altogether, 

 from 50 lbs. to 55 lbs. A pig of a year old has a lard membrane under 

 which the lard is secreted, but at that age it does not contain lard. 



