TRANSACTIONS OF THE SECTIONS. 29 



point of the acid) as much as 52G0 grammes were dissolved, to fall again to a low 

 figure with S0 3 + 8 HO. 



He did not doubt that these results would prove of great value to electricians iu 

 drawing their attention to the necessity of studying with care the strength of the 

 acid employed in their batteries. 



The action of heated concentrated sulphuric acid on zinc appears to divide itself 

 into two distinct phases, in one of which sulphuric acid is decomposed, and sul- 

 phurous acid given oft'; and the other in which water is decomposed and sulphu- 

 retted hydrogen given oft'. 



With mono-hydrated sulphuric acid only sulphurous acid is given off; with bi- 

 hydrated sulphuric acid, a large quantity of sulphurous acid is evolved, and only a 

 trace of sulphuretted hydrogen ; whilst with sulphuric acid containing 3 equivs. of 

 water, large quantities of sulphuretted hydrogen are produced, and only traces of 

 sulphurous acid. 



Dr. Crace-Calvert and Richard Johnson have also studied the action of sulphuric 

 acid ou copper and tin, and on brasses and bronzes ; also the action of hydrochloric 

 and nitric acids on the same metals and their alloys ; the interesting facts they 

 have observed will be found in a paper which they intend to publish shortly. 



On the Reactions of Cyanogen. Note on Glycocine, with Tables. 



By T. Faielet. 



On the Utilization of Blast- Furnace Slag. By Frederick George Finch, 

 B.A., D.Sc. (Bond.), F.G.S., Assoc. Boy. School of Mines. 



In this paper the author, after referring to the various attempts that have been 

 made both in this country and abroad to utilize the slag from iron-smelting fur- 

 naces, described a method now adopted to effect this object at several ironworks in 

 France and Belgium. The slag is there allowed to run direct from the furnace into 

 pits about 8 or 9 feet in diameter at the top, with sides sloping inwards towards 

 the centre, where they are about 3 feet deep. The mass is left for eight or nine 

 days to cool, when a hard, compact crystalline stone is obtained, which is quarried 

 and used for building purposes, but chiefly for paving-stones. It is on this last 

 application that its commercial value seems principally to depend. These paving 

 stones are laid down iu several provincial towns in France and Belgium, and also 

 in some parts of Paris. They appear to wear exceedingly well, and are certainly 

 superior to the grits and sandstones generally used for that purpose in those 

 countries. 



This manufacture, besides being the means of getting rid of what has hitherto 

 been a useless and cumbersome material, is found at the above works to answer in 

 a pecuniary point of view. The large area required for the pits would prevent its 

 adoption at many ironworks in this country. 



On some Minerals from South America. By David Forbes, F.R.S., Sfc. 



The following minerals were exhibited, and the results of their chemical examina- 

 tion reported : — 



Taltalite, a black mineral from the desert of Atacama, much resembling shorl, 

 and which proved to be a silicate of copper and alumina with part of the alumina 

 replaced by sesquioxide of iron, Domeykite, algadonite, and Darwinite, all from 

 Chili, being three distinct basic arsenides of copper, represented respectively by the 

 formulae Cu 8 As, Cu la As, and Cu ls As. The mineral Darwinite was proved iden- 

 tical with a mineral which had been about same time found at Lake Superior, and 

 which had been called Whitneyite. Telluriferous native bismuth, bismuth glance, 

 and Danaite from Sorata in Bolivia ; a new selenide of silver and nickel from near 

 Mendoza. Iodides, chlorobromides, and chlorides of silver, all crystallized from 

 near Copiapo in Chili, and au amorphous yellow mineral from the interior of the 

 desert of Atacama in Chili, which was an oxyiodochloride of lead. Three differ- 

 ently crystallized varieties of oxychloride of copper or Atacamite was shown from 

 the coast of Bolivia and Chile, along with several other rare or finely crystallized 

 minerals. 



