250 VI. METALS.—SuB-sALTs. 



cipitate a solution of common alum with a solution of subcarb. of 

 potash : mix the two sediments together while diffused in warm 

 water, strain and dry : a fine blue colour, but apt to turn red. 



Prussian green. The sediments of the two first processes 

 for making Prussian blue, before they have had the muriatic acid 

 added to them. 



2. Pour oxymuriatic acid upon fresh precipitated Prussian blue. 



Burnt Prussian blue. From Prussian blue heated in a 

 crucible ; it is as good a colour as mummy, and dries so well as to 

 require no drying oil to be mixed with it. 



BoRUSsiAS FERRi. Pvussiate of iroii. Calcine together dried 

 blood Sxij, subcarb. potash Siiij, and iron filings 5SS ; dissolve 

 the calcined mass in hot water, add vinegar as long as any sedi- 

 ment falls; filter; add a solution of green vitriol as long as any 

 borussiate is precipitated ; filter and dry. Used in intermittent 

 fevers, gr. iv to vj, ter quotidie. 



Phospiias FERRI. Dissolve iron turnings in muriatic acid, 

 and precipitate by adding phosphate of soda as long as any sedi- 

 ment falls, which wash and dry : blue. 



Oxyphosphate of IRON, Phosphas tritoxydi ferri. Dissolve 

 colcothar, or any red oxide of iron, in dilute muriatic acid, and 

 precipitate by phosphate of soda : white. Both are given from 

 gr, X to gr. XV, in cancer and scrofula. 



Chalybs pr.eparatus cum aceto. Steel fihngs wetted with 

 white wine vinegar, dried in the sun, and this frequently repeated ; 

 then levigated. 



Rust of iron, Ferri ruhigo^ LimaturcB ferri prceparatcR Cha^ 

 hjhis ruhigo, Carhonas ferri prcBparatus, Iron filings, or iron wire, 

 exposed to the air, and frequently moistened with water, to which 

 a small quantity of vinegar may be added ; then ground to pow- 

 der and washed over. 



Ferri carbonas, C, ferri prcecipitatus. A solution of 4oz. 

 of green vitriol in water is precipitated by another solution of 5 

 oz. of subcarb. of soda in water, the precipitate is washed with 

 warm water, and dried without exposure to the air, that it may 

 retain its green colour. 



S. By precipitating the solution of green vitriol with subcarb. 

 of potash, performing the process in hot water, and drying it by 

 steam. The preparations of iron are used as tonics in cancer, 

 scrofula, and in neuralgic affections. 



loDURET and Hydriodate OF IRON. Mix 126 parts of 

 iodine, and from 40 to 50 parts of clean iron filings in a flask 

 with 1500 parts; let heat be applied till the mixture becomes 

 clear, after which filter. The liquor is a solution of hydriodate 



