3 l 2 HARDENING OF STEEL.' 



cations prevent me from communicating much information t6 

 your valuable, journal, that would stand a chance, at least, of 

 being useful to many of your readers. 

 Common Te- To this circumstance alone, is to be referred the delay of my 

 nac,t y of ™ e * promised communication on the tenacity of the different metals. 

 The time necessarily required to complete experiments on this 

 subject, I have not yet been able to appropriate to that purpose j 

 and I am sorry that it must consequently still stand over, subject 

 however to a determination to fulfil my promise on the earliest 

 opportunity. 



In the irean time, a few remarks on interesting mechanical 



subjects, may not prove unacceptable. 



Hardening of The present paper contains some practical experiments on 



warping. hardening steel; the results of which have, in a great measure, 



proved successful in preventing warping: an inconvenience 



hitherto inseparable from the operation. 



The u?.ual pro- The process usually practised for hardening, is to heat the 



""sis the* aUd Steel S raduail y t0 a red heat » and lhen P^nge it into cold water, 

 work. which produces the desired effect j but it is a subject of regret 



with all workers of this metal, that the figure of their work, is 

 frequently changed by the operation, to such a degree, as to 

 render useless all previous labour, and accuracy of workman- 

 ship. 

 The subject The limited extent of human knowledge respecting the organ- 



does not re- t j za tion of matter, will only allow us to speak hvpothetically 

 quire theoreti- , . . i , "^ r , , 



ca l disquisi- as t0 tne occult causes to which these effects are referable. 



tions. I shall not, therefore, on the present occasion, cloud the inves- 



tigation of familiar operations, with the subtilties of philo-- 

 sophical disquisition j but proceed to the more useful part of my 

 task. 

 Heated steel Pyrometrical experiments prove that steel, when heated so as 

 contracts, by to carry expansion to its utmost limit, if suffered to cool gra- 

 first 'dni'ien- 1 * dua Hy and °^ its own accorcl > ViM return precisely to its original 

 sions. figure and dimensions. The detrimental effects produced by 



the operation of hardening, mus/ therefore be occasioned, by 

 some derangement of the particles, on the sudden expulsion of 

 caloric. Keeping this idea in my mind, I thought, perhaps, if a 

 piece of steel were repeatedly heated to different degrees below 

 the hardening point, and as frequently quenched in cold water^, 

 this process might operate ajteratively - 9 and induce a different 



arrange- 



