4380 L. M. Rutherfurd—Stability of the Collodion film. 
lated in order to obtain / in equation (5), it follows that equa- 
tion (4) is the simpler and the more readily worked numeri- 
call 
y: , 
If we call T the absolute temperature centigrade, then 
T=?’ +272°48, and equation (4) becomes(6)T= Care. in 
which equation the origin of codrdinates is at the vertex of the 
latter to the manometric capsule, so that the rarefied air in the 
hot tube cannot enter the tubing outside of the furnace. If 
the serrations of the manometric flames are too dim to be 
readily observed, they can be rendered distinctly visible, eve? 
in broad day-light, by the use of “carbonized ” gas, or by sifting 
into them the fine scrapings of lead pencil. In ascertaining the 
number of displacements produced by any temperature, the 
furnace-tube is slowly moved into the furnace, so that the 
October 12, 1872. 
= 
Art. L.—On the stability of the Collodion Film; by LEwIs M. 
RUTHERFURD. ; 
THE very numerous and concordant micrometric measures of 
direction 
th the utmost 
when applied to a a of glass properly albumenized. 
