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E. DIVERS AND T. HAGA 



have some experience to report concerning the preparation of potassium 

 nitrososulphate, that may be useful. 



Preparation of potassium nitrososulphate. — It is a mistake to suppose 

 that nitric oxide is slow to unite with potassium sulphite ; it is only 

 the insolubility of nitric oxide in water that retards the union, as the 

 use of suitably shaped vessels shows. We have had made for us four 

 strongly flattened conical bottles, and have connected them in series by 

 means of corks and tubes. The diameter of the flat bottom of the 

 bottles is, on the inside, 19*5 cm., while their inside height up to the 

 commencement of their neck is, axially, only 3 cm. With 100 cc. of 

 solution in one of them, there is a depth of only 3-4 mm. and a free 

 surface of nearly 300 sq. cm. The four bottles together give, therefore, 

 a surface of 1200 sq. cm. to 400 cc. of solution, further increased by 

 the circumstance that the salt, as it forms, grows up in small heaps 

 above its level. A concentrated solution, such as that containing 40 

 per cent, potassium sulphite and 5 per cent, potassium hydroxide, will 

 give a yield of crystals weighing 70 grams or more in 3 hours. In 

 cold or temperate seasons, external cooling is of little use ; motion of 

 the bottles, beyond an occasional tilting, is also uncalled for. Re- 

 placement of air at the beginning, and of nitric oxide at the finish, by 

 hydrogen is, of course, necessary, but the production of a, very little 

 oximidosulphonate or nitrite is hardly of moment, since these remain 

 in solution. The salt when drained on tiles is pure enough for most 

 purposes. For special work, like the present, it can be purified and 

 got in good crystals by dissolving it quickly in 4-5 times its weight 

 of water at 50-60°, containing 1—1*5 per cent, of potassium hydroxide, 

 but not without considerable loss. 



Process of reduction by sodium amalgam. — The amount of water 

 present with the salt seems to be without effect on the course of the 

 reduction ; the extremes we have used have been from 3 to 10 parts 



