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distinguislied by its crystalline appearance ; the fourth precijntate 

 is of a finely pulverulent form and insoluble either in potash-ley 

 or in acetic acid. 



Ammonia is also employed for saturating liquids, especially 

 those which have been precipitated with acetate of lead, in order 

 to i-ender them alkaline and so to produce another precipitate. 



Carhonate of ammonia (1 part in 9 parts water) acts similarly 

 to liquor of ammonia, but less energetically. Its principal use in 

 phyto-chemical operations is to remove completely any excess 

 of lead left from the precipitation with acetate of lead, and in this 

 respect it is superior to sulphuret of hydrogen, commonly 

 recommended, on account of greater simplicity and ease. 



Leys of potash or of soda (of 1-330 specific gravity) produce in 

 general the same appearances as ammonia, but act more decidedly. 

 They impart to coloured liquids a still darker colour. 



A precipitate, produced by potash or soda, and soluble in 

 an excess of the reagent, may be alumina partly or entirely. 



In the presence of ammonia-salts the ammonia is displaced by 

 potash or soda, and may be recognised either by the smell or by 

 the fumes obtained with acetic acid, and tested by holding a glass 

 rod moistened with the acid over the surface of the liquid. 



Carbonates of potash or of soda (1 part in 9 parts water) 

 possess in general the properties of potasli or soda-ley, but in 

 a less degree, and cannot dissolve alumina. They may be used 

 for removing an excess of oxyd of lead, when there is reason to 

 avoid the use of carbonate of ammonia. 



Solution of baryta (1 part Ba O + 9 HO in 19 parts water) 

 behaves towards coloured liquids similar to the alkalies; it 

 also produces precipitates which may be either alkaloids, from 

 which the acid is withdrawn, or components of baryta Avith 

 sulphuric acid, phosphoric acid, organic acids, or with sulistances 

 acting like acids, as pigments, resins, ttc. 



Lime-water (1 part Ca in 700 parts water) acts like solution 

 of baryta, but less decidedly; it does not precipitate sulphmic 

 acid but oxalic acid (which is not precipitable by diluted solution 

 of baryta), oxalate of lime being only soluble in mineral acids. — 

 Of the four organic acids, malic, citric, tartaric, and racemic, the 

 first is not precipitated by lime-water, either cold or hot; the 

 second is precipitated only in the heat, and becomes clear again on 

 cooling; the third yields cold a precipitate soluble in chloride of 

 ammonium; the fourth yields also a precipitate in the cold, but 

 insoluble in chloride of ammonium. 



Chloride of ammonium (1 part in 9 parts water) serves for 

 distinguishing tartaric from racemic acid. (See Lime-water). 



Chloride of baryum (1 part in 9 parts water). A precipitate, 

 obtained by means of it, contains certain anorganic acids. If it is 

 insoluble in hydrochloric acid, then it contains sulphuric acid; if 



