222 ANNUAL OF SCIENTIFIC DISCOVERY. 



tube was opened a good deal of gas escaped. Some of the results obtained 

 illustrate the pseudomorphosis of minerals. Chemical News. 



NEW PROCESS FOR THE MANUFACTURE OF SULPHURIC ACID. BY 



MR. SHANK. 



This process, the success of which is as yet very problematical, is based 

 upon the separation of the acid from gypsum by means of two successive 

 chemical reactions, namely, the decomposition of the sulphate of lime by 

 means of chloride of lead, and that of the sulphate of lead thus resulting 

 by means of hydrochloric acid. For this purpose, in a cistern of greater 

 length than depth, formed of sheet-lead, or masonry, or any other material 

 not affected by acids, are placed eighty-six parts of gypsum, or eighty-six 

 parts of calcined plaster, and one hundred and forty parts of chloride of 

 lead. To these are added a large quantity of warm water, and the whole 

 well mixed and stirred. An immediate reaction takes place, sulphate of lead 

 forming as a precipitate, while chloride of calcium goes into re-solution. The 

 stirring continues until the supernatant liquid is free of lead, which is to be 

 ascertained by the usual reagents. The liquor is then removed by decanta- 

 rion, while the sulphate of lead remains in the cistern. For the decompo- 

 sition of the sulphate of lead, hydrochloric acid is added in somewhat larger 

 proportion than that indicated by the chemical equivalents, the temperature 

 of the mixture is raised, and the reaction is finished. The chloride of lead 

 which forms is pi'ecipitated, while the supernatant liquid is nothing but a 

 solution of sulphuric acid. When cold, this is decanted and concentrated by 

 evaporation to the strength required in commerce. The chloride of lead 

 remaining in the cistern is washed with cold water, which removes the 

 greater portion of the adhering sulphuric acid, whereupon the same propor- 

 tion of sulphate of lime is added as before, and the whole process is recom- 

 menced. In this way the chloride of lead is used over and over again, 

 without any loss but that caused unavoidably during the manipulation. 



CHEMICAL SUMMARY. 



An Impervious Paper has been patented in England, which is prepared in 

 the following manner : A solution of soap is added to the paper-pulp in the 

 proportion of two ounces of solid soap to every gallon of pulp, and when 

 thoroughly incorporated, enough of a solution of alum is added to decom- 

 pose the soap and form a compound of the fatty acid and alumina. This 

 alumina-soap replaces the sizing, and renders the paper manufactured from 

 it impervious to water. 



Extract of Hops. M. Ramont asserts that he has obtained, by treating heps 

 by boiling water in a close vessel, an extract, which he calls ttoublonine, which 

 contains all the active, aromatic, bitter, and astringent principles of the hops; 

 and that by means of this extract the manufacture of ale may be greatly 

 ameliorated. Cosmos. 



Mi'.ans of Removing the Rancidity of Butter. Wild recommends that the 

 i uitter should be kneaded Avith fresh milk and then with pure water. He 

 s'ates that by this treatment the butter is rendered as fresh and pure in flavor 

 as when recently made. He ascribes this result to the fact that butyric acid, 

 to which the rancid odor and taste are owing, is readily soluble in fresh milk, 

 and is thus removed. Pliarm. Jour. 



