THE OPERATIVE CHEMIST. 
412 
The maker, of course, could never have made sulphuric acid 
by this method, at the price it was usually sold at, but that 
the unconsumed sulphur, mixed with the sulphate of pot 
ash, was sold to the maker of roll sulphur, at a’price nearly 
that of duty-paid sulphur, nine-tenths of which duty the sul 
phuric acid maker had returned to him, by his disregarding 
his oath, that the said sulphur was all consumed by him, in 
the making of oil of vitriol. 
In the present plan pursued by the English manufactu 
rers, the sulphur and saltpetre are in different vessels, and 
both are in furnaces separate from the chamber, and several 
feet distant ; consequently, all the advantages of the new 
French method, hereafter described, are obtained with this 
additional one, that sixteen charges can be burned in twenty 
four hours. 
It has long been an object with the manufacturers to 
procure sulphuric acid without the assistance of saltpetre: 
and this has been performed in England by Messrs. Hill and 
Huddock, who have taken out a patent for this purpose. 
They subject pyrites, or sulphuret of iron, in a state of pow 
der, to a strong red heat, in cast-iron cylinders, communicat 
ing with a chamber lined with lead containing water, into 
which, they say, they inject steam and a certain imponder 
able substance. As this substance is not mentioned, their 
patent is, of course, of no force. It seems probable that 
they use common manganese, or the black oxide of that 
metal, instead of saltpetre, either mixed with the pyrites, 
or in a separate cast-iron cylinder. 
It is found that the sulphur evolved by this means, and burn 
ing, produces sulphuric acid, which is immediately condensed 
in the water. The great advantages of this method are, that 
no saltpetre is necessary, and pyrites, a material which was 
before hardly put to any use, but that of making copperas, 
is the material employed for furnishing the acid. 
The improvements in the manufacture have been so great 
in England, that a pound of acid, which twenty years agc 
cost sevenpence, may now be had at the wholesale price for 
less than twopence. 
The quantity consumed in Great Britain is about three 
thousand tons a year. 
French manufacture of Oil of Vitriol. 
The principles of the French method of manufacturing 
this acid were the same as those of the method followed in 
England; but the details very different. Mons. Payen in-