132 Ohservcitlons on Mr. Klaprotk's Analysis, [Feb> 



By heating polished steel in pure azote, deprived of aqueous 

 vapour by sticks of potash over mercury, I found that no change 

 of colour took place. 



It appears evident, then, that the changes of colour produced 

 during the tempering of the steel are owing to the formation and 

 increase of a plate of oxide, and that they are mere indications 

 of, and not connected with, that change in the arrangement of 

 the particles of the steel which produce, the diminution of its 

 hardness. 



If you should not deem this statement of too little importance 

 for publication, you will ohlige me by inserting it in your^ 

 Journal, I am, dear Sir, 



Very sincerely yom's, 



HUMPHKY DAYY. 



Article VIII, 



Ohservaiions on Mr. KlaprctlCs Analysis of the Water of the 

 Dead Sea, By Alex. Marcet, M.D. F.R.S. one of the 

 Physicians to Guy's Hospital. 



(To Br. Thomson.) 



SIR, 



In the first number of your " Annals of Philosophy," you 

 have published an analysis of the water of the Dead Sea, 

 by Mr. Klaproth, the results of which appear to differ so much 

 from those which I laid before the Royal Society in 1807, 

 which were pt'blished in the Philosophical Transactions for that 

 year, that I think it necessary to offer a few observations in reply 

 to those which Mr. Klaproth has made upon our respective 

 analyses. 



I shall not trouble your readers with a repetition of the par- 

 ticulars of my analysis, which they may find detailed at full 

 length in the volum.e of the Transactions above-mentioned; but 

 as this experienced chemist has remarked, that the difference 

 between his results and mine was probably owing to what he 

 calls " the complicated processes and calculations " which I 

 followed, and as his paper does not convey the smallest idea of 

 the processes which he thus generally reproves, I am desirous of 

 stating, in a few words, the leading points of the method I 

 employed. 



My first object was to ascertain, with all the care and 

 accuracy of which I was capable, the composition of the prin- 

 cipal salts concerned in this analysis ; namely, the muriates of 

 lime, of m.agnesia, of soda, and of silver;"^ these appearing to 



* Some ©f these analyses of salts, the object of which was of a general import, 

 I have had the satisfaction of seeing contirmed by the researches of Messrs, 



■2 



