r^ I E. DIVEKR ANT) T. HAGA. 



The dipota.ssium snlt toi-ni.s detached hard crystals remarkable in 

 «hape, being like somewhat flattened, Aery acute octahedrons. The 

 crystals belong to the obli(|ue rhombic system (Raschig and Fock), 

 The analyses of Claus and Raschig established the composition of this 

 salt. Fremy's recorded results are improbable and insufficiently con- 

 <;ordant ; l)ut the identity of his sulplKCotdh' with dipotassium ox- 

 imidosul))honate is beyond doubt. 



According to Claus, the dipotassium salt is ])ractically insoluble 

 in cold water, and is very difficultly soluble according to Raschig. 

 Its crystals cnn indeed be washed without niiu-h loss, but the salt in 

 fine powdei- proves to be far from insoluble. It dissolves to the extent 

 of about one part in thirtv of water. When quite fi'ee from alkaline 

 salt, it is faintly acid to litnins. Ft readily forms supersaturated solu- 

 tions, as observed bv Rasdiig, and in the preparation of the salt the 

 inothef-liquors retain much more of it tlian could sim])lc water. We 

 find that of a saturated solution of sodium cliloride about 4 cub. cent, 

 are al)le to dissolve 1 gram of the dipotassium salt, but the solution 

 quickly deposits a compoiuid of the two salts. Other salts idso 

 increase its solubility. Potassium or sodiiun hvdroxide or normal 

 oximidosidphconate acts u|)oii it and thus affects its solubility. 



Fire-sixths normal potassiinii salt, IVoHNSoO;, KgNSA);, IL,f). — 

 There is really only one way of preparing this salt, namely, by dis- 

 solving up the dipotassium salt in hot solution of enough potassium 

 hydroxide (or salts equivalent to it) and crystallising. The dipotassium 

 salt should not be put into cold water or even potassium hydroxide, 

 and then the vessel heated to dissolve it, unless the mixture is con- 

 tinuously stirred ; foi' undissolved salt lying on the hot bottom of the 

 vessel is liable to hydrolyse. Observing this precaution, no simpler way 

 could be conceived to prepare the salt, all dilliculties being imaginary, 

 riie belief that the salt can be formed from the nitrite direct is un- 



