166 W. Crookes on the Wax-paper Photographic Process. 
kinds, and in every degree of purity: also to Mr. Maskelyne, 
for a valuable series of the chemical bodies of which the various _ 
waxes are composed; by means of these, I have been enabled ~ 
to examine the effect produced by saturating the paper with — 
bees wax from different countries, Myrica wax, Canauba wax, — 
China wax, spermaceti, ethal, stearic acid, stearin, palmitic acid, 
palmitin, paraffin, and various oils. 
22. I find that the action of the wax is purely mechanical, 
almost the only difference of effect produced by any of the above 
bodies, widely as they vary in their chemical nature, arising from 3 
a difference in their physical properties. 
aos 
EE a ne a 
Stearin, palmitin, and most of the oils, are too greasy in their 
nature to be advantageously employed. The fatty acids do not 
make the paper in the least greasy, but they injure the transpa- 
rency. China wax has almost too high a melting point, and 
gives a crystalline structure to the paper. Spermaceti also is too 
crystalline. Paraffin, ethal, and the waxes, produce very good 
, &.; the presence of a little spe 
does not much interfere, but as its price differs little fro n that 
of pure wax, it is not so common an adulteration as the other 
cheaper substances. . 
3. It will be unsafe to use the wax in the form of round thin 
tablets, about 4 inches in diameter, in which it is usually met — 
with, as in this state it is generally adulterated to the extent of — 
at least 50 per cent. . | a : 
"Asan article of commerce, it is next to impossible to obtain 
small quantities of wax sufficiently pure to be reliec upon. 
The only way I can recommend is to apply to one of the well 
known large bleachers, and trust to them for supplying the arti- 
cle ina state of purity. Whenever I have found it necessary 
to make such applications, my request has always been acceded 
to in the most cordial manner, and every information has been 
given with the utmost readiness. oe 
24. The other chemicals, (with the exception of the strong 
nitric acid, which any retail druggist will supply, and the wa 
which had best be distilled on the premises,) should be order 
direct from some manufacturing chemist, as otherwise, unless 
operator have a sufficient knowledge of chemistry to be able to 
detect any inferiority, there is danger of not having the article 
sufficiently pure. ee eee eee, 
The iodid and bromid of potassium should be ordered purified 
The nitrate of silver should be crystallized, not in sticks; i 
ought to be perfectly dry, and have no smell, acid or otherwise. 
There are usually two varieties of glacial acetic acid to be met 
; the purest must be used; it should be perfectly free from 
oat 
