TURPENTINE. 2J3 



the air until it has become of the proper consistency ; for^ 

 mending cells and for preventing running-in of the finishing 

 varnish (Northern Microscopist, ii, 1882). 



420. Turpentine, Venice Turpentine (CsoKOK, Arch. mik. 

 Anat., xxi, 1882, p. 353; PARKER, Amer. Mon. Mic. Journ., ii, 

 1881, pp. 229-30; Journ. Roy. Mic. Soc. (N.S.), ii, 1882, 

 p. 724). Venice turpentine (Terebinthina veneta) is the 

 liquid resinous exudation of Abies larix. It is seldom met 

 with in a pure state. The following are the directions for 

 preparing and using it given by Parker : 



Dissolve true Venice turpentine in enough alcohol, so that 

 after solution it will pass readily through a filter, and, after 

 filtering, place in an evaporating dish, and by means of a 

 sand-bath, evaporate down to about three quarters of the 

 quantity originally used. (The best way to tell when the 

 evaporation has gone far enough is to drop some of the 

 melted turpentine, after it is evaporated down to about three 

 quarters its original volume, into cold water ; if on being 

 taken out of the water it is hard and breaks with a vitreous 

 fracture on being struck with the point of a knife, cease 

 evaporation and allow to cool.) 



Or (CSOKOE), common resinous turpentine of commerce is 

 put in small pieces to melt over a water-bath, then poured 

 into a suitable vessel and allowed to cool. It should yield a 

 brittle, dark brown mass, not yielding to the pressure of a 

 finger. It is sometimes useful, in order to attain the right 

 degree of hardness in the cold mass, to add a little resinous 

 oil of turpentine to the melted mass, and then to evaporate 

 for several hours over the water-bath. 



This cement is used for closing glycerin-mounts; it is 

 applied in the following manner : Square covers are used 

 and superfluous glycerin is cleaned away from the edges in 

 the usual way. 



The cement is then put on with a piece of wire bent at 

 right angles (No. 10 12 wire is taken, and copper is the 

 best, as it gives to the turpentine a greenish tinge) ; the short 

 arm of the wire should be just the length of the side of the 

 cover-glass. The wire is heated in a spirit-lamp, plunged 

 into the cement, some of which adheres to it, and then 

 brought down flat upon the slide at the margin of the cover. 



