342 Mr. J. Napier on Damp Walls. 



and should tlie water or any of the substances used have organic matters 

 in them, these, with damp, are subject to decay, and produce salts that 

 will affect a wall. 



The analyses of these efflorescences have verified these statements. 

 The white coating upon bricks has been found to contain sulphuric acid, 

 alumina, magnesia, soda, and iron. Upon a brick wall near to where I 

 live, one side of the wall seems whitened over, leaving, generally, the 

 centre portion of the brick. I collected some of this, which was a fine 

 powder, resembling effioresced soda. This was tested, and gave sul- 

 phuric acid with a small proportion of hydrochloric acid, no alumina or 

 iron, but magnesia, soda, and a trace of Hme — all which I consider to 

 come from the lime between the bricks, which had been absorbed; 

 and the true source, the water used in mixing the lime when building. 

 Kuhlmann and Vogel have analyzed efflorescence upon walls, and give 

 as their general composition sulphate of soda and potash, carbonate of 

 soda and potash, and chloride of sodium and potassium, and their opinion 

 is, that these salts are from the lime, taking no notice of the water used. 

 Whichever be the source, we have found the composition of the efflores- 

 cence to vary according to cuxumstances. A snowy efflorescence grow- 

 ing out from plaster to the depth of half an inch, a sample of which is 

 exhibited, I found to be almost wholly composed of sulphate of soda, 

 having a mere trace of magnesia, lime, and chlorine. Another sample, 

 upon a different wall, different lime being used, but in the same locality, I 

 found to be of the same composition, and also, that mostly all the spring 

 waters in the locality (Partick) contain soda. In a house built last 

 spring, the walls of which outside were pretty well dried during sum- 

 mer except the two first courses of stone from the ground, they 

 have been damp all along, mostly, in my belief, from the found ; but 

 during the late dry weather these stones have become coated over with 

 a white floury efflorescence. I washed off some of this, and found by 

 testing that the water was slightly alkahne, and gave soda, magnesia, and 

 a little lime, with sulphuric and muriatic acids. These salts I believe to 

 be mostly from the water absorbed from the found. 



In a house I occupied in Swansea, there had formerly been a rent in 

 the side wall, of nearly two inches wide, which had been filled up by 

 lime. Against this wall a wing had been erected, so that when I occu- 

 pied it this wall was not exposed to the weather ; nevertheless, all along 

 this rent, and for 12 inches of the plaster on each side, no paper would 

 adhere for any length of time. In damp weather it became damp, in 

 dry weather it effloresced ; and though brushed off again and again, 

 the sovirce seemed inexhaustible. I collected ten grains of this efflor- 

 escence, and submitted it to analysis, and obtained the following, in 

 100 parts :— 



