THE TECHNOLOGIST. [Nov. 1, 1864. 



160 ON CHEMISTRY APPLIED TO THE ARTS. 



hours, when the disagreeable operation of removing the mass and 

 clearing the hair was proceeded with. The black dye communicated 

 to the hair in this process was due to the sulphur of the hair com- 

 bining with the lead of litharge, and forming black sulphuret of 

 lead. The present process consists in cleaning the hair thoroughly 

 with a strong alkaline soap, or a little weak alkali, then carefully 

 applying a solution of nitrate of silver, and lastly a solution of rnono- 

 sulphuret of sodium. 



Wool differs from hair chiefly by its property of felting, which it 

 owes to its numerous cross lines or serratures, as they are termed ; the 

 finer the wool the greater the number of its serratures. Thus, whilst 

 Mr. Goss has found in the finest Saxony wool 2,720 of these serratures 

 in a single inch in length, he only found 2,080 in an inch of South 

 Down wool, and 1,850 in Leicester. The wool of sheep can be classed 

 under two heads, that is, into long wool and short wool. Certain classes 

 of sheep will maintain the type or quality of their wool under every 

 circumstance. Such are the original types of South Down, Norfolk, and 

 Dorset, all of which are short wool, and all these sheep feed upon fine 

 and short grass. It has been observed that if they are fed upon coarse 

 grass, their wool will also become coarse. This is also true with Welsh, 

 Scotch, and even Spanish merinos. A further proof that this view 

 appears correct is, that the long-woolled sheep, such as those of Leicester, 

 Lincoln, and Kent, feed in valleys where grass is long and coarse. In 

 all cases the size of the animals appears also to correspond with their 

 class of food. Another curious fact is the facility with which one type 

 of sheep will merge into another if they change food and climate. Thus 

 many attempts have been made to introduce into France our Leicester 

 breed, the wool of which is so remarkable for its fineness, length, and 

 silvery appearance. Still, after four or five years' residence there, the 

 wool has lost its most valuable qualities. In fact, the sheep are no more 

 the Leicester breed. The coarse wool of sheep, however, such as those 

 of Devonshire, does not appear to be so rapidly influenced by any change 

 of climate which the animal may undergo. The aptitude which various 

 kinds of wool have for dyes is also interesting. Thus the wool of one 

 kind of sheep will not dye with the same facility as that of another ; 

 and wool dyes much more uniformly if the animal has been washed 

 before shearing, than when the washing is performed upon the wool 

 afterwards. Lastly, the wool removed by the liming process before 

 described will be far interior in dyeing properties to wool taken from the 

 same kind of animal during life. It may be interesting to know the 

 best method of removing these irregularities. I was engaged during my 

 assistantship at the Gobelins in investigating this matter, and I found 

 that the best plan was to steep the wool for twenty-four hours in lime- 

 water, and then to pass it through weak hydrochloric acid. Wool, as it 

 leaves the animal, is not fit for either dyeing or spinning. Thus when 

 wool is washed with water it yields a large quantity and variety of sub- 



