1821.] Netv Scientific Books. 157 



barytes be washed upon the filter, fresh inconvenience arises ; the 

 sulphate must be detached from the filter, or they must be weighed 

 together; and, in either case, an error is easily made, especially if the 

 operator is not well skilled. 



The other mode of precipitating the sulphuric acid, and which it is 

 here proposed to adopt, is to take a solution of muriate of barytes of 

 known strength, and to pour this solution into that which contains the 

 sulphuric acid, until precipitation ceases. When the precipitation is 

 nearly complete, the solution of muriate of barytes should be added 

 only by drops. The solution, after each addition of the muriate of 

 barytes, is to remain till it becomes clear before any more is added. 



To expedite the process, a portion of the liquor may be filtered, and 

 a drop of muriate of barytes added to it. The same filter will serve 

 for the whole operation. There is no danger of the sulphate of barytes 

 passing the filter in this operation ; this only occurs when the water 

 contains but little or no saline matter in solution. 



The quantity of sulphuric acid, and, consequently, that of the sul- 

 phur, is given by the weight of the muriate of baryte6 employed ; the 

 equivalent number for sulphur being 20116, and that of crystallized 

 muriate of barytes 152'44. It will be sufficient to make this propor- 

 tion : 152*14 : 20-116 :: the quantity of muriate of barytes employed 

 is to a fourth term, whicji is the quantity of sulphur sought. 



This process, it appears, is used at the laboratory of the powder 

 manufacturers in France, and it is stated to determine the quantity of 

 sulphur within l-500th or l-1000th part. The common salt is used to 

 moderate the deflagration ; and the carbonate of potash is necessary 

 to prevent the sulphuric acid from being volatilized. — (Ann. de Chita. 

 et Phys.) 



Upon this process, I would merely remark, that there is no danger 

 of sulphate of barytes passing through the filter, if the solution from 

 which it is precipitated be hot ; and it very readily subsides in hot 

 water. I have not found any difficulty in ascertaining the quantity of 

 sulphate of barytes, provided a double filter be used; the outer one to 

 serve, of course, as a counterpoise to that which contains the sulphate 

 of barytes. — Ed. 



Article IX. 

 NEW SCIENTIFIC BOOKS 



PREPARING FOR PUBLICATION. 



Lectures on Botany, by Anthony Todd Thomson, Esq. FLS. 



Dr. Conquest will publish in a few weeks, a Second and enlarged 

 Edition of his " Outlines of Midwifery, &c." with Copper-plate 

 instead of Lithographic Engravings. 



JUST PUBLISHED. 



A Treatise on the Nature and Treatment of Scrophula, describing 

 its Connexion with Diseases of the Spine, Joints, Eyes, Glands, &c. 

 founded on an Essay to which the Jacksonian Prize, for the Year 

 1818, was adjudged by the Royal College of Surgeons. To which is 



