1870.] Mining. 131 



so vividly described are only examples of that mimic vegetation 

 often so beautifully displayed in stones by the oxide of manganese. 

 Those arborescent forms and shaded outlines will be familiar to 

 many who have visited the heights of Clifton, where the " landscape 

 marble," as it is called, is nicely polished and sold to the many 

 visitors to that delightful locality. 



' La Houille/ a French journal devoted to the colliery interests 

 of France is, from, the excellence of many of the articles contained 

 in it, commanding a considerable amount of attention. It has re- 

 cently given some notices of experiments made by MM. Kouille and 

 Co., on producing a light for mines by atmospheric air, impregnated 

 with petroleum vapour by being passed through the more volatile 

 of the coal-shale oils, or other hydro-carbons. We refer to this only 

 to condemn it. In the first place, the introduction of volatile 

 hydro-carbon vapour into a coal mine is only adding another to the 

 many dangers by which the coal miner is surrounded ; and in the 

 second place, the process has been long known, often tried, and it 

 has always failed ; because the vapour of the petroleum is speedily 

 deposited from the air, and at a comparatively short distance from 

 the reservoir the air ceases to be inflammable. 



Our ' Colliery Guardian ' calls attention to the " Lighting of 

 .Mines" with common gas, by an apparatus devised by Messrs. 

 Church and Co. We are told that the light is produced by the 

 combustion of a mixture of ordinary carburetted hydrogen gas with 

 atmospheric air in certain proportions, and that from the manner 

 in which the combined fluids are consumed no flame is produced. 

 We have not seen this lamp. We do not know how the mixture 

 of air and gas is burnt ; we presume from the description given that 

 we have a modification of the well-known Oxyhydrogen Lamp — 

 something of either the Bude-light, or the Drummond-light type. 

 This, however, we do know, that the statement that " no flame is 

 produced" is one which cannot be maintained; and while it tends 

 to deceive those who are not familiar with the laws of combustion, 

 it may prove highly dangerous, by leading the unwary to make 

 experiments in explosive atmospheres, under the idea that where 

 there is no flame there can be no ignition of the surrounding gases. 

 That the flame may not have the character of the ordinary flame 

 of a gas-burner may be true; but the very description given 

 proves that a flame of great intensity is produced by the combustion 

 of the mixed gases. 



At the Hayle Foundry, in Cornwall, there have been some 

 experimental trials of a system of pneumatic stamps, which have 

 been witnessed by a large number of practical miners, who are most 

 favourably impressed with the results. The following brief descrip- 

 tion will, we believe, convey a sufficiently clear idea of the general 

 principles of this machine : — 



k 2 



