Other stone buildings in the town have suffered, but in very different degrees, and some have quite escaped, proving the necessity of careful selection of material wherever coal fires abound. In Birmingham the action of coal fires is assisted by other sources of acid vapor. The process of “pickling” brass castings, _i.e._, brightening their surface, by dipping first in common nitric acid (“pickle acky”) and then in water, is attended with considerable evolution of acid fumes. Besides this very widespread use of acid, there are several chemical manufactories that throw still more acid into the air immediately surrounding them. As an example of the action of the atmospheric acids of London upon building stones, I have but to name the Houses of Parliament, which have only been rescued from superficial ruin by the patchwork replacing of certain blocks of stone, and various devices of siliceous and other washings that have been carried out at great cost to the nation. That such an unsuitable material should have been used is disgraceful to all concerned. The ruin commenced before the building was finished. At the time when its erection commenced there were abundant evidences of the ruinous action of London atmosphere on some kinds of stone and the capability of others to resist it, for while many modern buildings are peeling and crumbling, some of the oldest in the midst of the city show scarcely any signs of corrosion. The Birmingham and Midland Institute was established and in practical operation a few years before the present noble building was erected. I was the first teacher there and conducted the Science classes in the temporary premises in Cannon street. Having observed with some interest the disintegration of St. Philip’s Church and other buildings, I was anxious for the safety of the new Institute buildings, and accordingly made some experiments upon the material proposed to be used by the architect. My method of testing was very simple, and as the practical result has verified my anticipations I think it might be adopted by others. First, I immersed some lumps of the stone in moderately strong solutions of sulphuric and hydrochloric acids successively, and observed whether any visible action occurred after some days. There was none. I then roughly tested the crushing pressure of small samples in their natural state, and subjected similar sized pieces to the same test after they had been immersed in the acids. I found thus that there were no evidences of internal disintegration even after several days’ immersion, and therefore inferred that the stone would stand the acid vapors of the Birmingham atmosphere. This has been the case with that portion of the building that was built of the material I tested. As I know nothing of the stone which is used for the extension of the building under the present architect, Mr. Chamberlain, I am unable to make any forecast of its probable durability.