CHEMISTEY. 



PEODUCTION OF VERY HIGH TEMPER ATUKES. 



SAINTE CLAIEE DEVILLE has published an extended description of the 

 methods employed in his laboratory to produce high temperatures, and his paper 

 possesses great value and interest. For operations on a small scale, Deville 

 employs a lamp of peculiar construction, in which the vapor of oil of turpen- 

 tine or any other liquid hydro-carbon is completely burned by means of a 

 powerful artificial blast of air. The lamp in question would be scarcely intel- 

 ligible without a figure, and we must refer for fuller details of its construction 

 to the original memoir. By its means a heat, sufficient to melt feldspar, can 

 be easily produced, provided that the table bellows employed is of sufficient 

 size and power. [We have found it in practice less safe and convenient than 

 the gas blast lamps with sixteen jets, introduced by Sonnenschein, but it gives 

 a higher temperature.] The other apparatus discovered by the author is a blast 

 furnace, in which platinum and many other substances can be fused. It con- 

 sists of a cylinder of fire clay 18 centimetres in diameter and somewhat higher 

 than its width. This may be surmounted by a dome to prevent the escape of 

 the coals from the force of the blast. This cylinder rests upon the edge of a 

 hemispherical cavity connecting with a good forge bellows. A circular piece 

 of cast iron pierced with openings about 10 millimetres in diameter, and dis- 

 posed round the edge of the plate, forms the bottom of the cylinder and sepa- 

 rates it from the cavity below. The author employs as fuel, cinders from the 

 hearth of a furnace heated with the dry coal of Charleroy. These cinders are 

 found mixed with pieces of coal, and are sifted upon a sieve with square holes 

 of 2 millimetres in the side. What passes through the sieve is rejected. The 

 coals employed must vary from the size of a small pea to that of a nut. The 

 crucible is placed in the centre of the cylinder and surrounded with kindled 

 wood, upon which pieces of coal of the size of a nut are laid, and upon these 

 the proper fuel of the furnace. The blast is then forced in slowly and gradually 

 increased. The force of the maximum temperature begins about 2 or 3 centi- 

 metres above the iron plate, and is only 7 or 8 centimetres high. The coals 

 above remain cold from the transformation of the carbonic acid into carbonic 

 oxyd, which gas in the author's furnace burns with a flame 2 metres in height. 

 The heat produced by this arrangement is called by the author the " blue heat," 

 from its peculiar tint. In it the best ordinary crucibles run down like glass. 

 The author uses three kinds of crucibles. The first is of quicklime, and is made 

 of weU burned lime slightly hydraulic, which is out with a knife or saw into 



