151 
Preparation of Ox- Gall. 
mitting the specific gravity of this wire to be 7788. 
and a pound will contain cubic inches. Therefore 
649 
64 
= .00000199316 inches for 
2304 ^ I 
649 * 49553 X 36 ~ 32159897 
the area of its section, and consequently, .0091593 for 
its diameter. 
Another circumstance which confirms our opinion re- 
lative to the formation of the drawing plates, is, that one 
of these large plates reduces 1400 chiliograms, from the 
largest size to that of No. 6, which is about the thick- 
ness of a knitting needle ; and 400 chiliograms are also 
reduced from this size to the smallest carding wire, by 
being passed twelve times successively through a single 
small plate. This we apprehend could not take place, 
unless they were very perfect. 
[The Editor will esteem it a favour, if any person possessing the 
above mentioned numbers, would allow him the opportunity of giv- 
ing this paper more fully than is here done, arid of obtaining an en- 
graving of the plate.] 
No. 20. 
Method of preparing Ox-Gall in a concentrated state 
for Painters , and for other Uses . By Mi chard Ca» 
thery.* 
Sir, 
It has been long a desideratum to find out a method 
of preparing ox-gall for the use of painters, so as to 
avoid the disagreeable smell, which it contracts by keep- 
ing in a liquid state, and at the same time to preserve its 
useful properties. I have invented a method of doing it 
* Nicholson, vol„ 30. p, 154, From Trans, of Soc. of Arts, vol. 28. p. 106. 
Ten guineas were voted to Mr. Cathery for this invention, 
