S4 ^'^ ''''« Purily of Tirugi and Medicines,' 



phuric acid, and lOO parts of the acetite of lead Indicate 30 per cent, of acid. The prefence 

 of muriatic acid may be afcertaincd by adding to a like faturated folution of this fah, a few 

 grains of nitrate of filver. If the alkali did not contain any combination of muriatic acid, 

 it will have no efFe£l upon it ; but if the minuteft quatitity of muriatic acid is prefent, a 

 white precipitate will be produced, which after fome time acquires a bluifli hue ; neither 

 nitric nor acetic acid will redifiblve it. Calcareous earth is raanifefted in a fimilar manner, 

 by adding drop by drop, a folution of oxalic acid. The quantity of the precipitate thus 

 obtained, if calcareous earth be prefcht, gives the proportion of this earth in a given quantity 

 of the fait fubmitted to the experiment. 



Pure fait of tartar, which flands all thefe tefts, Is of a fnow whitenefs, inodorous, perfeftly 

 dry, and foluble without a«y fediment in anequal quantity of pure cold water, it then con- 

 tains generally 70 parts of alkali, 23 carbonic acid, and 7 of water. 



Water of Kali. Pham. Lond. Solutlofi of Salt of Tartar, 



When fait of tartar is expofed in a fliallow veflel to the adlion of a moift atmofphere. It 

 loon deliquiefces, or attradls fo much water, as Is fufficient to render It liquid. This fluid 

 ought to contain at leafl: one part of alkali in four. If fo, it feels extremely greafy or flip- 

 pery between the fingers, on account of it diiTolving the epidermis, and converting it into 

 a kind of foap. If the alkali made ufe of has been pure, this fluid is perfectly colourlefs^ clear, 

 void of fmell, and polTefles all the properties of a pure fait of tartar. But as the alkali made 

 ufe of in general, by our chemifts, is far from being fo, the article we meet with has gene- 

 rally a yellowifh tinge, a difagreeable, fomewhat urinous, fmell, and foon depofits a confider- 

 ble quantity of earthy Infoluble matter. 



Water of Pure Kali. Ph. L. Solution of Cauflic Pot-afb. ' 

 As It is called In our Pharmacopeia, ought to be a folution of cauftic alkali in water, of 

 fuch a ftrength that an txa(3; pint {hall weigh juft 16 oz. troy. When well prepared, it is as 

 limpid as water, and inodorous. It ought not to occafion any precipitate with lime water, 

 neither ought it produce the leaft efftrvefcence with acids. A redundancy of lime is* befl. 

 inown by blowing into this fluid, through a tobacco pipe, or other tube. If too much 

 lime be prefent, the fluid will then turn turbid. Inllead of obtaining this article In the 

 fliops, we take common foap-leys of the foap manufadlurers, diluted with water, hence this 

 article Is always yellow, and hence the redundancy of lime, and other heterogeneous falts 

 found in it. ' ' 



Prepared Natron. Ph. L. Mineral Alkali. 



As It Is no eafy taik to obtain mineral alkali perfeBly pure, we need not expeft to find it 

 fo in commerce. This article, if prepared agreeably to the diredtidns of the Royal Col- 

 lege of Phyficlans, cannot but be contaminated w\ih fulpkate and muriate of foda. But 

 what is ftill worfc, the fraudulent chemifts mix fulpliate of foda with it intentionally. Itv 



order 



