342 On the Cutting of Steel by Soft Tron. 
ing a mixture of salts. having these acids in their composi- 
tion, that the whole may pass to the state of nitrites by the 
agency of air, heat, and moisture. 
Variable quantities of these two acids mav be formed, 
under the different circumstances in which the two gases 
are mixed; “this perfectly explains the differences in the 
results of those who have operated with them.” ; 
A great degree of reliance may be placed on the indica- 
tions of nitrous gas as employed in the method of Gay Lus- 
sac; but for accurate experiments it will probably never 
supersede the use of hydrogene and the electric spark in 
Volta’s eudiometer, or in the improved form of that appa- 
ratus proposed by Dr. Ure. 
November 12, 1823. 
an 
Art. XVIII—On the Cutting of Steel by Soft Iron. 
Eprror. 
Philadelphia, execute, with a common foot, lathe, opera- 
lave however since repeatedly seen the experiment 
succeed, in the most perfect manner, at the manufactory of 
< arms, belonging to Eli Whitney Esq. near this town. As 
Bho rapidity, that the motion became entirely impercepti- 
