158 Intelligence and Miscellaneous Articles. 



pends upon the quantity of sulphuric acid carried over ; for hy a 

 carefully conducted operation the ingredients mentioned give about 

 300 parts of crude acid of the density of about 1*455 ; when the 

 operation has been too quickly conducted the density and weight of 

 the product is greater. 



In order to separate the sulphuric acid and the small quantity of 

 chlorine which the product contains, it is to be shaken with a slight 

 excess of a saturated solution of sulphate of silver, and the chloride 

 of silver formed is separated by nitration; the acid is then to be put 

 into a capacious capsule, and artificial carbonate of barytes added 

 till all the sulphuric acid is precipitated, and even till a little oxi- 

 chlorate of barytes is formed. The liquor now contains only oxi- 

 chloric acid, with a little oxichlorate of barytes and of silver, and is 

 to be distilled, in the apparatus already described, with the addition 

 of ice, separating the first product, which is only water, and ascer- 

 taining that the acid is coming over by test paper. The distillation 

 is to be carried on to dryness, but taking care not to decompose the 

 oxichlorates of barytes and silver, for then the rectified oxichloric 

 acid might contain traces of chlorine. 'The oxichloric acid thus ob- 

 tained is perfectly pure, colourless and transparent ; its specific gra- 

 vity is between l - 717and 1*800, and it is oleaginous like sulphuric 

 acid ; 500 parts of oxichlorate of potash yielded 150 parts of this 

 concentrated acid. — Journal de Pharmacie et de Chimie, June 1842. 



ON THE ACTION OF WATER ON LEAD. BY PROF. CHRISTISON. 



In a second paper on this subject, just published in the Transac- 

 tions of the Royal Society of Edinburgh (vol. xv. part 2. p. 271), 

 Dr. Christison states the following as the results of his entire inves- 

 tigation : — 



" From the facts now detailed, together with the results of my 

 former inquiries, the following conclusions may be drawn as to the 

 employment of lead pipes for conducting water. 



" 1. Lead pipes ought not to be used for the purpose, at least 

 where the distance is considerable, without a careful chemical ex- 

 amination of the water to be transmitted. 



" 2. The risk of a dangerous impregnation of lead is greatest in the 

 instance of the purest waters. 



" 3. Water which tarnishes polished lead when left at rest upon 

 it in a glass vessel for a few hours, cannot be safely transmitted 

 through lead pipes without certain precautions *. 



" 4. Water which contains less than about an 8000th of salts in 

 solution, cannot be safely conducted in lead pipes, without certain 

 precautions. 



"5. Even this proportion will prove insufficient to prevent cor- 

 rosion, unless a considerable part of the saline matter consist of car- 

 bonates and sulphates, especially the former. 



" G. So large a proportion as a 4000th, probably even a consider- 



* " Conversely, it is probable, though not yet proved, that, if polished 

 lead remain untarnished or nearly so for twenty-four hours in a glass of 

 water, the water may be safely conducted through lead pipes.'-' 



