496 INVESTIGATIONS RELATIVE TO ILLUMINATING MATERIALS. 



Third experiment. — Winter-pressed lard-oil. 



Temi)eratnre before mixiug - 70° F. 



Temperature after mixing 165'^ 



Difference 95° 



Fourth experiment. — Crude lard-oil. 



Temperature before mixing 6C° F. 



Temi^erature after mixing 164° 



Difference... 98° 



REFRIGERATION OF THE OILS. 



Tliose experimented upon were whale, sperm, refined lard, and crude 



lard. 



First experiment. 



At 30°.2 F. they were all sirupy ; in the crude lard-oil a yellowish 

 solid began to separate. 



At 2G°.6 the sperm-oil began to solidify. 



At 24°.8 the refined lard began to yield a white precipitate. 



At 17°.G the whale-oil was a thick sirui), without deposit. The crude 

 lard-oil was quite hard. The pure lard-oil was not as hard as the crude 

 lard-oil. The sperm-oil was not as hard as the pure lard-oil. These ex- 

 periments performed in test tubes. 



Second experiment. 



Upon pure winter-pressed lard-oil, in a test tube. 

 At 170.0 F., begins to deposit flakes of solid matter. 

 At 14° is quite thick. 

 At 10°.4 it is perfectly solid. 



If, now, the temperature rises, a small portion of the oil remains solid 

 until the temperature reaches 44°.6. 



Third experiment. 



The oils were placed in large cylinders and exposed to a temperature 

 of 24° 8 F., with the following results : 



1. Crude lard-oil, much sediment. 



2. Sperm-oil, ditto. 



3 Pure refined lard-oil, a little sediment. 



4. Winter-strained lard-oil, very little sediment. 



5. Whale-oil, no sediment. 



In the use of sperm-oil, it was found that the purer it could be ob- 

 tained the better, and hence it was the custom to strain the oil through 

 clean white sand previous to using it, and also the drippings. In the 

 case of lard however, it was found that removing all the solid matter 

 diminished its photometric power. 



