ELISHA MITCHELL SCIENTIFIC SOCIETY. 21 



crude gum which exudes from the i)ine is called Turpentine, in 

 common life one of the volatile products of the distillation of 

 this gum is called Turpentine. In other words, in trade the 

 distlllant is Turpentine, in common life the distillate is Turpen- 

 tine. WImt we call Turpentine is in the trade called '^spirits," 

 or spirits of Turpentine. In most text-books on chemistry 

 mention is made of "oil of turpentine," a term not used in com- 

 merce, meaning spirits of Turpentine. 



What is Rosin? Rosin is the residue left in the still after the 

 extraction of the "spirits." It is strained, cooled by exposure 

 to the air, and allowed to crystallize. 



You will, therefore, please consider the term Turpentine as 

 meaning the crude gum (before distillation); the term "spirits," 

 or Spirits of Turpentine, as meaning the most important sub- 

 stance distilled off from this gum, and Rosin the residue left in 

 the still, drawn off while hot, strained and crystallized. 



There are three kinds of Turpentine, viz. : virgin, yellow-dip 

 and scrape. 



There are four kinds of spirits, viz.: white spirits and 1st, 2d 

 and 3d ''shade:' 



Of Rosin, excluding "opaque Rosins," there are fourteen dif- 

 ff^rent kinds, viz.: A., B., C, D., E., F., G., H., L, K., M., K, 

 W. G. and W. W. Of these the highest grade is W. W. (water- 

 white), l)eauti fully clear and transparent, and almost colorless. 

 Then W. G. (window-glass), also clear and transparent, but a 

 shade darker in color than the W. W. Then N. Rosin, also 

 clear and transparent, but a shade darker tlian W. G. And so 

 on down to A., omitting L. and J., each letter signifying a Rosin 

 of darker color, until when A. is reached the Rosin is black and 

 allows no ray of light to pass through. And I may say just 

 here that there are two main causes of the difference in color 

 between Rosins: 1st. The quality of the Turpentine. 2d. The 

 care bestowed upon the process of distillation. W. W. Rosin is 

 almost colorless, A. ftosin is black, and between the two lie 

 various shades of very light amber, a dark wine-color, and black. 



