W. Crookes on the War-paper Photographic Procees. 168 
common water, once with distilled water, and then placed in a 
: slanting position against a wall, face downwards, to drain on 
| clean blotting paper. 
: 11. The vessel in which the wax is melted, must be contrived 
SO as never to allow of its reaching a higher temperature than 
212° Fahr., or decomposition of the wax might ensue. I have 
found the most convenient apparatus to be, a tin vessel 15 inches 
i square and 4 inches deep, having a tray which holds the wax 
fitting into it, about 1 inch deep. The under vessel is to be half 
7 filled with water, and by keeping this just at the boiling tem- 
__ perature, the wax above will soon become liquid. 
_ 12. The best source of heat is that known as the gauze gas 
burner, it being free from smoke or dust, and not liable to 
_ _ blacken anything placed over it. It consists of a common argand 
burner fixed on a rather low and heavy iron stand, which is sur- 
uare inch fastened over the top. _ y connecting this burner 
by means of vulcanised indian rubber tubing to the gas pipe, it 
can be moved about the table to any convenient position, The 
mixture of gas and air formed inside the cylinder, is to be lighted 
e the wire gauze; it burns over this with a large and nearly 
Shea msequence. So j 
ee a plate of silver; this is very expensive, and seems 
- wove blotting paper, - éedium thickness. But this is not suff- 
J 
as the quantity required is trifling. A convenient size for the 
still is about two gallons; it may procured ready made, with 
_ worm &c. complete, of any large dealer in chemical apparatus, 
_ Tt will be found far more economical both in time and trouble, 
a 
