Sulphur and Phosphorus. 409 



that by employing crystallized native Sulphur, which had 

 been recently sublimed in nitrogen, I should avoid the pre- 

 sence of any foreign matter, yet I am inclined to believe 

 that this is not the case; for bv subliming some similar 

 sulphur in nitrogen, I find that litmus paper placed in the 

 upper part of the retort is slightly reddened. 



When potassium is made To unite with sulphur, if the 

 retort employed is not lined with sulphur, some of the po- 

 tassium is destroyed by acting upon the glass ; and when 

 large quantities of sulphur are used, it is very difficult to 

 decompose the whole of the sulphuret of potassium by an 

 acid ; sulphuretted hydrogen likewise is soluble in muriatic 

 acid : and this circumstance led me to under-rate the quan- 

 tity of sulphuretted hydrogen given oft* in experiments of 

 this kind *. 



In acting upon sulphuretted hydrogen by potassium in my 

 early experiments, I used large quantities of the gas and of 

 the metal ; and in these cases I have reason to believe that 

 the violence of the combustion occasioned the decomposi- 

 tion of a considerable quantity of the gas ; and, in conse-r 

 quence, led me to form erroneous conclusions concerning 

 the nature of this curious operation. 



Jn all late experiments in which sulphur or sulphuretted 

 hydrogen was concerned, I have used muriatic acid saliw 

 rated with sulphuretted hydrogen over mercury. I have 

 employed sulphur distilled from iron pyrites in vacuo, which 

 did not in the slightest degree affect litmus paper, and [ 

 have combined it with potassium in retorts of green-glass, 

 or plate- glass lined with sulphur and filled with very pure 

 nitrogen or hydrogen. In making potassium act upon sul- 

 phuretted hydrogen, I have employed the gas only in the 

 quantities of from one to three cubical inches, and have made 

 the combination in narrow curved tubes of green-glass over 

 dry mercury. With all these precautions, and after having 

 made a great number of experiments, I am notable to gain 

 perfectly uniform rtsuks. Yet there is a sufficient corre- 

 spondence between them to enable me to form conclusions, 

 whieh I may venture to say cannot be far from the truth. 

 When one grain of potassium, which would give by the. 



* This circumstance has been '.jointed out by MM. Gay Luaac and 

 T/heoard, i° :1 ' a P L - r P r »nted in the Journal de Physique for December, in 

 which there gentlenler! endeavour to show that, whether potassium ha? been 

 acted upon by large or un II qiUU hi- ot suiplnn ard under all circum- 

 stances, it evolves a quantity 01 gas exactly e^aal to that which it produces 

 by the action of water. I ha\ been able \o gain no results i > precise on 

 this subject. I have in another place (the same journal in whieh their me- 

 nioir has appeared) offered some observations on their inquiries. 



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