36 Experiments on the Yolk of Wool. 



sides the substances already mentioned, yolk contains a cer- 

 tain quantity of animal matter; for it gives by distillation 

 very sensible traces of ammonia, and an oil the foetid odour 

 of which has a considerable resemblance to that furnished 

 by animal matters. 



Yolk then is composed, 1st, of soap with a base of pot- 

 ash, which forms the greater part of it : 2d, a small quan- 

 tity of the carbonate ofpotash : 3d, a considerable quantity 

 of acetite of' potash: 4th, lime, with the state of the com- 

 bination of which I am unacquainted : 5th, a small por- 

 tion of muriate of potash : 6th, a peculiar animal matter, 

 to which I ascribe the particular odour of yolk. 



In my opinion, all these matters, which are essential to the 

 nature of yolk, are not found in it accidentally, for I have 

 always found them in a great number of the {JifTerent kind* 

 of wool both of Spain and of France. 



I shall not speak here of the other matters insoluble in 

 water, which are found also on wool, such as the carbonate 

 of lime, sand, filth of every kind, — these being evidently 

 accidental. 



It still remains to determine whether all the matters 

 which exist in yolk are the product of cutaneous perspira- 

 tion accumulated and thickened on the wool, or whether 

 they are contracted in cots or other places where sheep re- 

 side. It is very certain that all the elements proper for the 

 formation of the matters contained in yolk are found in the 

 excrements of these animals, and in the vegetables which 

 serve them as litter. I cannot, however, believe that the 

 whole is the effect of beds of dung ; on the contrary, I am of 

 opinion that the perspired humour is the principal source. 



The analysis of dunghills would give us no certain in- 

 formation on this subject, because the matters found in 

 them might have been deposited by the sheep themselves. 



But even if we suppose, what appears to be very proba- 

 ble, that the principles of yolk arise from the humour of 

 perspiration, do these matters issue in this manner from 

 the body of the animal, and do they not experience any 

 change during their remaining on the wool ? This is a 

 question to which it would be difficult to give a decisive 

 answer. We can only presume that in wool, as in all very 

 compound substances deprived of movement, there are ef- 

 fected changes, of which, in the present case, we know nei- 

 ther the mode nor the cause. 



Yolk being, as already seen, a real soap soluble in water 

 and in alcohol, it appears that there can be no better me- 

 thod of scouring wool than to wash it in running water. 



But 



