TRANSACTIONS OF THE SECTIONS. 69 



immediately takes place. The carbon of the coke combines with the 

 oxygen of the steam, forming, in the first instance, carbonic acid, 

 ■which, by passing on through a further portion of the red-hot carbon, 

 is converted into carbonic oxide ; the hydrogen gas, together with the 

 oxide before-mentioned, is applied to the furnace by means of a jet 

 inserted within the blast-pipe tongue ; the pressure upon the gas, of 

 course, being equal to that upon the blast. The pipes require to be 

 replenished with the brays about every twelve hours, which is con- 

 veniently effected by means of a plug fitted to the top of each of them. 

 At first some difflSculty arose from destruction of the pipes ; but as 

 the melting point of cast-iron is so much higher than the temperature 

 required to decompose water, it was evident that the cause of the mis- 

 chief lay in the construction of the heating furnace. This haS been 

 remedied, and the apparatus seems now to be very durable. The pre- 

 sent one at Oldbury has been in operation for some months, and the 

 pipes are apparently little the Avorse for wear. The quantity of fuel 

 required to keep them hot is from twelve to fifteen cwt. of small coal 

 for twelve hours ; and as the steam is obtained from the engine-boilers, 

 and the fireman of the hot-air apparatus has time enough to attend to 

 it, the expense, with the exception of wear and tear, is a mere trifle. 

 The wear and tear, in every probability, Avill be very moderate, and 

 Mr. Dawes has sufficient reason to conclude that the cost will not be 

 more than three or four shillings for every hundred thousand feet of 

 gas, every foot of Avhich is, of course, equivalent to a certain quantity 

 of fuel. Various experiments have now shown not only that the qua- 

 lity of the iron is very much improved by this process, but that the 

 producing power of the furnace, at the same time, has greatly increased. 

 In conclusion, Mr. Dawes observes, that any advantages it may be 

 found to possess in the smelting of iron must be equally valuable in 

 the reduction of other metals. 



On the Influence of Voltaic Combiyiation on Chemical Action. 

 By Dr. Andrews. 



In dilute sulphuric acid, composed of one atom of the dry acid and 

 eight atoms of water, the solution of distilled zinc is permanently acce- 

 lerated, by connecting it with a plate of platina, immersed in the same 

 liquid, so as to form a voltaic combination. In acid, containing seven 

 atoms of water, the ordinary action is at first increased, and afterwards 

 rather diminished by contact with platina. But when zinc is heated in 

 acid, containing less than this quantity of water, the connexion with 

 platina transfers the evolution of gas, from the surface of the positive 

 to that of the negative metal, and at the same time diminishes its 

 quantity, and consequently retards the rate of solution of the zinc. 

 The formation of a galvanic circle exerts, therefore, a reverse effect on 

 the solution of zinc in sulphuric acid containing more or less than 

 seven atoms of water. The principal circumstances which influence 

 these results are the adhesion of the hydrogen gas to the surface of the 



