Chemistry and Physics. 127 
f ro- 
tation are those which are at the same time endowed with the feeblest 
doubly refracting powers.—Ann. de Chimie et de Physique, xl, 156, 
February, 1854. “é 

Cannas 
: \\ 
é \\Uiararavars, 

glass bottle, into the neck of which is firmly ground with emery a fun- 
nel (a, fig. 2) having a short but large spout. These are made suffi- 
“888s plate. Within the outer funnel the common filtering funnel is 
raced Festing loosely against its side so as to allow a free e of air. 
a 
pede represented at e, fic. 2. The plate is about three inches in diam- 
ter, and when tedtin, # the ali d, (see fig. 1) covers the opening 
smpletely and permits sufficient lateral motion to bring the stream of 
Water on different paris of the precipitate. A vacuum is readily ob- 
