3 of Photography to the Microscope. 189 
carefully. The use of the rod and the lever and achromatic 
lens has already been mentioned. After. tl co 
has been thrown on the ground glass it 
tered from 80 seconds to 10 minutes, ace 
ain nearly unal- 
the power and 
Collodion.—This article when furnia@easby 1 
can of course be used, though it is better for more than one reason 
to be independent of the dealers if possible. A considerable num- 
ber of samples of pyroxyline were prepared according to differ- 
ent receipts and sensitized variously. The very simple process 
Sa by Waldazk, on page 266 of his treatise on Photo- 
graphy, was found with slight modifications to yield an excellent 
article.* The strength of the sulphuric acid was slightly greater 
than recommended by him, no watey was added, the temperature 
also was slightly higher, at the time of the immersion of the 
cotton: a more prolonged washing than that prescribed in this 
work is desirable. This collodion can be sensitized with advan- 
tage by the iodid and bromid of cadmium in the proportion of 
four to one. A receipt published in Humphrey’s Photographic 
Journal has lately been used by me with very good results.t 
No. 2 
No, 1, ; aac 
Plain collodion, 1 oz. Plain collodion, 1 oz. 
odid of ammonium, 5 grains. tassium, 5 gr 
Bromid of potassium, 8 do. Bro: 
ked eye, while other 
‘ with all care, yield 
i Cincinnati, 1860. 
* Treatise on Photography by Chas. Waldack, 
+ Humphrey’s Journal, Joseph H. Ladd, New York. 
pakers of repute 
