292 Ehemical Preparations. 
purpose, others will judge. My first object was to obtain a per- 
fect and clean solvent for caoutchouc. My second one will ap- 
pear by and bye. ‘Take sulphuric acid (and water 2*) equal weights, 
mix, and when cold add a quantity of it to a quantity of oil of 
turpentine, and agitate thoroughly : the acid will become colored 
by uniting with, or charring the resin; let the acid subside, and 
decant the clear spirits. Repeat the operation until the acid sub- 
sides without being discolored. The oil of turpentine thus pre- 
pared, with warmth and strong solar light, is, as I believe, a per- 
fect solvent of caoutchouc. ‘This process is somewhat expensive and 
troublesome, and after a great number of fruitless trials with various 
articles, I found that alkalies and alkaline earths, especially lime, 
would attack resin, but not pure oil of turpentine. On distilling oil 
of turpentine from caustic lime and water, I found a great deal of re- 
sin remaining in the still on the first operation, but none at any sub- 
wise found that the oil thus purified was not a good solvent of caout- 
chouc, probably ‘because in distilling the oil it had acquired water 
which it held in combination. 
3. SAFE PROCESS FOR MANUFACTURING GUN POWDER. 
Ihave always supposed that gun powder, the materials being the 
same, was good in proportion to the intimacy with which its comp 
nent parts were united. “The almost infinite subdivision of paints 
effected by grinding them in oil, it appeared to me might be imitated 
by grinding the materials composing gun powder in some fluid, 
which these materials were insoluble. Nitre and charcoal are insolu- 
ble in alcohol, and sulphur is nearly so; hence ina properly constructed 
mill these substances may be ground in alcohol, and the greater a 
of the alcohol drained and pressed out, whilst the small residue ¥ 
evaporate with great readiness. I made the experiment, and obtain: 
ed a good powder at the first operation. Alcohol, however, W45 rather 
too volatile, and a substitute that was less so, was 4 desideratum- This 
substitute was found in pure oil of turpentine : the resin having been 
previously completely removed, the oil when used was readily evap” 
xed with the acid: ” 
* The author has, in his MS., omitted to state what is mi 
ould blacken 9nd 
have ventured to fill the void as in the text; for the strong acid W 
char the oil of turpentine. —Ep. 
