42 • REPORT — 1861. 



his aim had been to erect works on sound chemical principles. The fii-st furnace 

 he erected was successful in calcining the smaU ores with a small expenditure of 

 fuel and labour, with elimination of all the sulphur from the ores if that was re- 

 quired ; and it enabled him to send all the sidphur so eliminated into the vitriol- 

 chambers as sulphurous-acid gas. Very soon afterwards he erected additional 

 furnaces, and all the sulphuric acid made at his works since the end of 1861 had 

 been made from these small ores by similar fm-naces. The amount of sulphur 

 wasted in copper-smelting, and which could be economized for the use of such 

 calcining furnaces as he had erected, was something enormous. It had been 

 estimated at 70,000 tons per annum, which at the present time would be worth 

 455,000/. A more recent improvement, and which he has now in successful ope- 

 ration, is the combining of these calcining furnaces with the ordinary copper-smelt- 

 ing furnace, in such a manner that the flame of the smelting furnace, instead of 

 passing directly to the stack or chimney, is made to pass imder the calciner, and 

 affords suflicient heat to efiect the calcination of the ore required by the smelter ; 

 thus at once saving 30 to 33 per cent, of all the fuel required for copper-smelting, 

 that being about the proportion required by the calcination part of the process. 

 Another advantage of this mode is that the calciner is so placed that when a 

 charge of ore is required for the smelter, it is at once passed in a red-hot condition 

 by a shoot from the calciner directly on to the bed of the smelter. In the present 

 mode of manufacture, the ore is dropped out of the calciner into a cave under it, 

 and is there di-edged with water imtil completely damp, and by barrows is then 

 removed, and in this wet condition is thrown into the highly heated smelting fur- 

 nace. The saving of fuel, labour, destruction of fiu-naces, and nuisance from escap- 

 ing gases must be very evident. 



On the Precipitation of Aluminous Silicates from Solution. By Dr. Sullivan. 



On the Colouring of Agates. By Professor Tennant, F.G.S. 

 Some details were given respecting the stracture of agate, and the artifices re- 

 sorted to by the workmen of Oberstein in colouring the agate ornaments manu- 

 factured at that place and distributed over Europe. A large nimiber of specimens 

 were exhibited, not only of ornaments, but of the stones, both cut and uncut, the 

 foiTuer well adapted to show the structm-e. The black colour is produced by 

 steeping the specimens in oil, and then blackening them by the action of sulphuric 

 acid. 



On the Rational Formula of Eosaniline. By J. Alfred WANKtTif. 



According toHofmann,the empirical formula for anhydrous rosaniline is CjpHjgN,; 

 the salts being Cjo Hjg Nj, XH and C^o H,5, N^SXH, whilst the base on being liberated 

 from one of its salts takes the form C.,(, H|g N,, Hj O. 



It will be apparent that anhydrous rosaniline is just equal to a base consisting of 

 two atoms of toluyl and one of phenyl along with three atoms of nitrogen. 



This manner of constructing the foi-mula of rosaniline, which appears to be adopted 

 by some chemists, derives a remarkable confirmation from the circumstance dis- 

 covered by Hofmann, that it is requisite to employ a mixture of toluidine and 

 aniline in the manufacture of rosaniline, neither toluidine nor aniline alone being 

 capable of yielding the dye. 



Notwithstanding this capital fact, it is quite certain that rosaniline is not 



In several reactions rosaniline displays three atoms of easily replaceable hydrogen. 



