SULPHURIC ACID 



959 



the largo vitriol- chamber, and there exercises its well-known reaction upon its aeriform 

 contents. The economy thus effected in the sulphuric-acid manufacture is such that 

 for 100 parts of sulphur, 3 of nitrate of soda will suffice, instead of 9 or 10 as usually 

 consumed. 



The flue or waste-pipe serves to carry off the residual gas, which should contain 

 nothing but the nitrogen of the atmosphere, which has been introduced. 



There are at least two plans at present in use for burning the sulphur continuously 

 in the oven. In the one, the sulphur is laid on the hearth (or rather on the flat hearth 

 in the separate oven, above described,) and is kindled by a slight fire placed under it ; 

 which fire, however, is allowed to go out after the first day, because the oven becomes 

 by that time sufficiently heated by the sulphur-flames to carry on the subsequent com- 

 bustion. Upon the hearth, an iron tripod is set, supporting, a few inches above it a 



1944 



OIL OP VITKIOE MANUFACTORY. 



a. Sulphur burner or furnace. 



6. First leaden chamber. In the manufactory from which the above sketch was made this 

 chamber was 70 feet long, 20 feet wide, and 20 feet high ; but the size varies considerably in different 

 establishments. 



d 



smaller leaden 



e. Steam-boiler. 



/. Flue pipe or chimney of the furnace. 

 g. Steam-pipe. 



Ji. The flue or pipe conveying the residual gas from the first to the second leaden chamber. 

 i. Pipe conveying the gas, not absorbed in the first and second chamber, into the third. 

 k. Flue or waste pipe. 



I. Mnnhole, by which the workmen enter the chamber when the process is not going on. 

 m. Pipe for withdrawing a small portion of sulphuric acid from the chamber, in order to obtain 

 Its sp. gr. by the hydrometer. 



hemispherical cast-iron bowl (basin) charged with nitre and its decomposing portion 

 of strong sulphuric acid. In the other plan, 12 parts of bruised sulphur and 1 of nitre, 

 are mixed in a leaden trough on the floor with 1 of strong sulphuric acid, and the 

 mixture is shovelled through the sliding iron door upon the hot hearth. The succes- 

 sive charges of sulphur are proportioned, of course, to the size of the chamber. In one 

 of the largest, which is 120 feet long, 20 broad, and 16 high, 12 cwts. are burned in the 

 course of 24 hours, divided into 6 charges, every fourth hour, of 2 cwts. each. In 

 chambers of one-sixth greater capacity, containing 1,400 meters cube, 1 ton of sulphur 

 is burned in 24 hours. This immense production was first introduced at Chaunay and 

 Dieuze, under the management of M. Clement Desormes. The bottom of the chamber 

 should be covered at first with a thin stratum of sulphuric acid, of sp. gr. 1'07, which 

 decomposes hyponitric acid into oxygen and binoxide of nitrogen ; but not with mere 

 water, which would absorb the hyponitric acid vapours, and withdraw them from their 

 sphere of action. The crystalline compound, described below, is often formed, and is 

 deposited, at low temperatures, in a crust of considerable thickness (from one-half to 

 one inch) on the sides of the chamber, so as to render the process inoperative. A 

 circumstance of this kind occurred, in a very striking manner, during winter, in a 

 manufacture of oil of vitriol in Kussia ; and i<<. has sometimes occurred, to a moderate 



