Experiments on the Yolk of Wool. 3f 



But I must observe that there is on wool a small quantity 

 of greasy matter not in combination with the alkali, and 

 which adhering to the wool makes it retain something 

 pitchy, notwithstanding the most careful washing. 



But if wool be put into tubs, and the quantity of water 

 necessary for moistening it be poured over it ; and if it be 

 suffered to remain in that bath, for some time, often treacling 

 it down, it will be much better scoured, and become whiter 

 by washing it afterwards in running water. 



Scourers are accustomed to macerate their wool in pu- 

 trefied urine, and it is generally believed that the ammonia 

 which is thus developed effects the scouring j but I have 

 6ome reasons for thinking that this alkali is of no use. This 

 effect is owing rather to the yolk itself, or to some other 

 principle -of the urine, to uree for example ; and my opi- 

 nion is founded on the following circumstance : — I put 

 washed wool into a current of water in a mixture of sal- 

 ammoniac and common potash. This mixture had a strong 

 odour of ammonia; and yet the wool was not scoured, 

 because this alkali does not form, or forms only with diffi- 

 culty, a saponaceous compound with the greasy matter of 

 wool. I am of opinion then, from these observations, that 

 putrid urine is almost useless in scouring wool, at least so 

 far as its ammonia is concerned. 



If the utility of putrid urine be at least doubtful, it is on 

 the other hand very certain that fresh urine would be very 

 prejudicial in regard to the proposed end ; for the soap con- 

 tained in yolk would incontestably experience a decomposi- 

 tion by the acid of urine, which would precipitate the grease 

 on the wool. 



I suspect that the same effect would be produced by 

 washing wool in water containing earthy salts, which, as 

 is well known, decompose alkaline soaps. For this reason 

 it is always prudent to employ for this purpose the purest 

 water possible to be obtained. 



The case is not the same with soapy water ; it perfectly 

 completes the scouring of the wool, and at the same time 

 gives them more whiteness. If wool then, after being 

 washed in running water till it gives no more filth, be suf-> 

 fered to macerate for some hours in a twentieth part only of 

 its weight of soap, dissolved by, a sufficient quantity of tepid 

 water, often treading it down, it will be entirely freed from 

 the small portion of grease still adhering to it, and then ex- 

 hibit a softness and a degree of whiteness which it would 

 pot have acquired without this operation. 



Yolk itself a little concentrated, as I have alreadv an- 

 C 3 nounced, 



