36 



VniversHy of California Publications in Zoology [Vol.15 



at the time of weighing, ic the apparent weight (in mmg.) of the im- 

 mersed sinker, and w' a constant weight (in mmg.) selected so as to 

 facilitate computation. This formula for a particular sinker is 



S - =1.024905+0.000033(20°— e°)—0.00003984((c— 8860) 

 4 



Its accuracy is indicated below where the specific gravity. iS -. of dis- 



4 



tilled water as given in the standard physical tables is compared to 



that computed by the formula : 



In order to obtain an additional cheek on the accuracy of this 

 method, the specifie gravity of a series of samples determined in this 

 way wa.s compared with that determined with a pycnometer. The 

 results are listed below : 



