Ure's Dictionary of Che?nisfiy. 347 



protoxide of chlorine, ilieatchlorine of Sir H. Davy. GadoLnite,tlie siliciate 

 of yttria, was first observed by Dr. WoUaston to display a similar lively 

 incandescence. The variety of this mineral, with a glassy fracture, answers 

 better than the solintery variety. It is to be heated before the blow- 

 pipe, so that the whole piece becomes equally hot. At a red-heat it catches 

 fire. The colour becomes greenisli-grev, and the solubility in acids is 

 destroyed. Two small pieces of gadoliiiite, one of which had been heated 

 to redness, were put in aqua regia ; the first was dissolved in a few hours ; 

 the second was not attacked in two months. Finally, Sir H. Davy observed 

 a similar phenomenon on heating hydrate of zirconia. 



" The verbal hypothesis of Ihermoxygen by Brugnatelli, with Dr. Thorn- 

 son's supporters, partial supporters, and semicombustion, need not detain 

 us a moment from the substantial facts, the noble truths, first revealed by 

 Sir H. Davy, concerning the mysterions process of combustion. Of the 

 researches which brought them to light it has been said, without any hyper- 

 bole, that ' if Bacon were to revisit the earth, this is exactly such a case 

 as we should clioose to place before him, in order to give him, in a small 

 compass, an idea of the advancement which philosophy has made since the 

 time, when he had pointed out to her the route which she ought to 

 pursue.' 



" The coal mines of England, alike essential to the comfort of her popu- 

 lation and her financial resources, had become infested with fire-damp, or 

 inflammable air, to such a degree as to render the mutilation and destruc- 

 tion of the miners, by frequent and tremendous explosions, subjects of 

 sympathy and dismay to the whole nation. By a late explosion in one of 

 the Newcastle collieries, no less than one hundred and one persons perished 

 in an instant ; and the m?sery heaped on their forlorn families, consisting 

 of more than three hundred persons, is inconceivable. To subdue this 

 gigantic power was the task which Sir H. Das'y assigned to himself; and 

 which, had his genius been baffled, the kingdom could scarcely hope to 

 see achieved by another. But the stubborn forces of nature can only be 

 conquered, as Lord Bacon justly pointed out, by examining them in the 

 nascent state, and subjecting them to experimental interrogation, under 

 every diversity of circumstance and form. It was this investigation which 

 first laid open the hitherto unseen and inaccessible sanctuary of Fire." 



We recommend the whole article to the diligent perusal of 

 our readers. He has transplanted with fidelity the beautiful 

 and invaluable facts, first disclosed to the world in Sir H. Davy's 

 papers on flame, published in the Philosophical Transactions. 

 Dr. tJre arranges the phenomena of combustion under six 

 heads : — 



" 1st, The tempferature necessary to inflame different bodies. 2d, The 

 nature of flame, and the relation between the light and heat which compose 

 it. 3rf, The heat disengaged by different combustibles in burning, ith. 

 The causes which modify and extinguish combustion, and of the safe-lamp. 

 5th, Invisible combustion. 6tk, Practical inferences. 



Our author has announced in the introduction, a systematic 



work on chemistry. 



" If the public," says he, " after this larger specimen of my chemical 

 studies, shall deem me qualified for the task, I may promise its completion 

 within a year from this date. The work will be comprised in four octavo 

 volumes, and will contain the results of numerous investigations into the 

 various objects of practical chemistry, joined to a systematic view of its 

 principles. By several simple instruments, tables, and rules of calculation, 

 chemical analysis, the highest and most intricate part of the science, may, 

 1 apprehend, be, in many cases, brought within the reach ot the busy manu- 

 facturer ; while, by the same means, such accuracy and despatch may be 

 ensured, as to render the analysis of saline mixtures, complex minerals, 

 and mineral waters, the work of Jin hour or tw o ; the proportions ot ine 

 constituents being determined, to one part in the thousand. 



