In the manufacture of sulphuric acid, the use of ordinary solder is impracticable, since it would soon be corroded. The following method was introduced some years ago for forming sulphuric acid chambers, and the concentration pans. Two edges of lead being placed in contact, were flattened down into a long wooden groove, and secured in their situation by a few brass pins driven into the wood. The surfaces were next brightened by a triangular scraper, rubbed over with candle-grease, and then covered with a stream of hot melted lead. The riband of lead thus applied, was finally equalized by being brought into partial fusion with the plumber’s conical iron, heated to redness; the contact of air being prevented by sprinkling rosin over the surface. The autogenous soldering apparatus will greatly simplify the above method. The advantages to be derived from the new process, are by no means confined to lead: the apparatus may be employed in using for solder either the common alloys, or pure lead, to unite zinc, and iron, and lead, with iron, copper, and zinc. It may be substituted also with advantage for the common blow-pipe and lamp of the enameller in all their applications to the soldering and joining performed by the aid of these instruments by jewellers, goldsmiths, tinmen, manufacturers of plated goods, of buttons, &c. The flame produced by the combustion of the gas may be most economically employed for heating soldering irons. A few seconds suffice to bring the iron to the desired temperature, and it can be kept at that temperature for many hours without being liable to burn, nothing more being necessary than to regulate the flame by means of cocks, and the workman need not be obliged to change his iron, or even to leave it for a single moment. Hence there is not only a considerable saving in manual labour, but also in fuel, which in most cases is of greater consequence. Such are a few only of the advantages of this simple and beautiful invention, which is now very extensively adopted in France, and will doubtless get into extensive use in this country, when its merits are more generally known. It may be here stated, in justice to some of our own ingenious countrymen, that after this method had become extensively known, M. Richemont’s claim to the invention was disputed. We have been informed, that previously to the year 1833, a Mr. Mallet had employed an apparatus constructed on the same principle, and used in a similar manner, as that already described as the invention of M. de Richemont. In LOUDON’S _Encyclopædia of Cottage Architecture_, published in 1833, the following passage occurs:--“Mr. Daniell, of King’s College, London, has since published the same thing as new, and of his invention: however, I can establish priority by my laboratory journal.” FOOTNOTES: