MECHANICAL AND USEFUL ARTS. 83 



which the hot products of the combustion of the fuel are sent through a 

 large mass of blocks of fire-brick, which extracts the heat from them; 

 the air to be heated being afterwards forced through the same mass, 

 in the reverse direction, in order to withdraw the heat from them, 

 the air thus heated being then sent into the blast furnace. 



The economy of heat obtained by the new stoves as compared with 

 the ordinary ones is most striking when using gas as fuel ; for it has 

 been found by direct experiment that the heat passing away from the 

 ordinary stoves amounts to more than 1250°, and as the tempera- 

 ture produced by the combustion of the gas is about 2000°, the 

 difference of about 750° is all the heat that is taken up by the 

 ordinary cast-iron pipes ; whereas the regenerative stoves do not part 

 with the heat at a higher temperature than about 200°, and as the 

 temperature produced is about 2000°, the difference, or 1800°, is 

 used in place of only about 750°. 



As regards utilizing the waste-gas from the top of a blast- furnace, 

 Mr. Cowper has very properly remarked that recent experience, both 

 in this country and abroad, has fully proved that there is no real 

 difficulty in accomplishing this, either on the plan adopted at the 

 Ebbw Vale works, or on that of Mr. Charles Cochrane, and all 

 doubt on the subject is now removed ; the regenerative stoves are 

 also particularly well adapted for being heated by gas, as there are no 

 iron pipes to be injured by the gas flame. — Mechanics Magazine. 



GAS MAKING. 



Mr. W. Clark has patented certain improvements in the Manu- 

 facture of Gas, and in apparatus for the same. These relate, 1, to a 

 new method of distilling matters furnishing gases which are only 

 slightly carbonated ; which matters the patentee distils with products 

 furnishing carbonated gas, having very great lighting power, for the 

 purpose of obtaining therewith gas more fit for lighting and heating. 

 2. To a peculiar apparatus for the distillation of the mixture of these 

 two matters. This improved method is applicable equally for the 

 distillation of peat, which furnishes a gas having like lighting power 

 mixed with carbonate of h} T drogen, produced from matters which 

 furnish by distillation a lighting gas ; the principle of the said method 

 being to effect at the same time the distillation of gas from the two 

 matters introduced in proper proportions by hastening the distillation 

 of the one and retarding that of the other ; thus, the two gases 

 resulting from peat and tar will chemically combine and furnish a 

 rich suitable gas. In order to obtain such simultaneous distillation, 

 he makes use of a distilling apparatus which retards the distillation 

 of the carburets of hydrogen. — Mechanics Magazine. 



NEW GAS FOR LIGHTING. 



Superheated steam, charged with coal-tar, produces, with mar- 

 vellous rapidity, and at an exceedingly low price, any quantity of a 

 very rich gas for lighting. Careful analysis is composed of free 

 oxygen, 1*8; oxide of carbon, 3; carbonic acid, 5 '8 ; bicarburetted 

 hydrogen, 17 '8; and protocarburetted hydrogen, 17'9. Compared 



F 2 



