and particularly the Tartrates* 389 



after many hours, and the re-crystallized acid is nearly colour- 

 less. 



2. The readiest mode of obtaining a proper red tartrate of 

 iron, is, by mixing the liquid red sulphate with solution of tar- 

 trate of potash in equivalent proportions. Sulphate of potash 

 precipitates in a crystalline powder, (the solutions being some- 

 what concentrated) which may be separated from the blood-red 

 liquid tartrate of iron by filtration. When to this ferreous 

 solution, its own bulk of alcohol, sp. gr. 0.840 is added, so as 

 to form a proof spirit menstruum, decomposition immediately 

 ensues, indicated by a cloudiness, and a precipitate of a treacly 

 consistence and aspect, which collects at the bottom. The 

 supernatant liquid is nearly colourless, and contains hardly any 

 iron, but much tartaric acid. The viscid precipitate soon 

 hardens into a brittle mass of subtartrate of iron, insoluble in 

 water. Thus it appears, that a spirituous menstruum is not 

 at all adapted for holding red tartrate of iron in solution, 

 though Madeira and Teneriffe wines of common strength 

 answer very well. 



When the above concrete precipitate is treated with water, 

 acidulated with tartaric acid, it readily dissolves, with the re- 

 production of red tartrate of iron. 



The subtartrate, when newly thrown down, is fusible, at the 

 heat of 180° or 190° F. It burns reluctantly in the flame of 

 a spirit-lamp, with a faint ignition, and a slight smell of 

 caromel. 



3. The potash-tartrate of iron, as prepared by the process of 

 the London Pharmacopoeia, is a powder of an olive-green colour, 

 occasionally tinged with brown. When 100 grains of it were 

 heated to the temperature of 160° F., they lost 4 grains ; but 

 this loss will vary according to the manner of preparing it. By 

 dull ignition, in a platinum crucible, it emits a lambent blue 

 flame, and is converted into red oxide of iron and carbonate of 

 potash, amounting together to 52 grains. The alkali was dis- 

 solved out with water, and tested with acid. It indicated 18 

 grains of potash, equivalent to 46.5 of tartrate of potash. The 



