THE VENETIAN TURPENTINE METHOD 109 



tial thing is to provide a small, air-tight place in which the soda lime 

 may work. 



Instead of soda lime you may use fused calcium chloride or the 

 white sticks of sodium hydroxide. 



We are now ready for the transfer from absolute alcohol to the 10 

 per cent Venetian turpentine. Make the transfer quickly. Pour off the 

 absolute alcohol and place the dish, with the material, in the exsicca- 

 tor; then pour on the 10 per cent turpentine, and immediately put on 

 the cover. This is better than to pour on the turpentine and then try to 

 get the dish well placed in the exsiccator. 



The greater the surface of soda lime exposed, the more rapid will be 

 the concentration of the Venetian turpentine. The concentration 

 must not be too rapid. Not less than 2 days should be allowed for the 

 concentration of 30 c.c. of the turpentine in an ordinary Minot watch 

 glass. 



Great care must be taken not to let any of the soda lime, or other 

 drier, get into the turpentine. 



When the lime has become saturated, it may be heated until dry, 

 and then used again. If material is put into an exsiccator with nearly 

 saturated lime, the turpentine becomes milky. If the material is very 

 valuable, wash in absolute alcohol until entirely free from any milky 

 appearance, and start again in 10 per cent turpentine. If the material 

 can be replaced, throw away the milky stuff and start at the beginning. 

 It may teach one not to put material into an exsiccator with half- 

 saturated lime. 



In Tucson, Arizona, the Venetian turpentine method is easy, with 

 no need for an exsiccator. Dr. J. G. Brown tells me that the air is so 

 dry that the 10 per cent Venetian turpentine can be left exposed to the 

 air until it concentrates, just as we leave the 10 per cent glycerin. 



As soon as the turpentine has attained the consistency of pure 

 glycerin, it may be exposed to the air without any danger from mois- 

 ture; but the turpentine would soon become too thick for mounting. 

 If the turpentine has become too thick, thin it with a few drops of 

 absolute alcohol or with 10 per cent or any thin solution of Venetian 

 turpentine. 



Mount the material in a few drops of the Venetian turpentine and 

 add a cover. Tapping on the cover with the handle of a needle or 

 scalpel will often separate the filaments so that they are more con- 

 venient for examination. Square covers may be used since it is entirely 



