298 Dr. W. Gregory s Economical Mode of 



2ndly. I find that with less than 1 atom of chlorate to 1 of 

 each of the other ingredients, the mass cannot be kept 

 fused, and, consequently, the mixture is imperfect. 3rdly. 

 From the large proportion of chlorate employed, a corre- 

 sponding quantity of chloride of potassium is left, which 

 interferes with the subsequent purification of the hyper- 

 mangate of potash; and, lastly, since 1 atom of chlorate of 

 potash loses 6 of oxygen by heat, while 1 of binoxide of 

 manganese requires only 1 of oxygen to convert it into 

 manganic acid (the change which occurs in this stage of 

 the process,) we lose f ths of the oxygen. 



After many trials, I found the following process to answer 

 remarkably well. 



Take of binoxide of manganese, 132 parts (3 atoms) of 

 fused potash 147 parts (3 atoms), chlorate of potash 124 

 parts (1 atom). Dissolve the potash in a very small quan- 

 tity of water, and add to the solution the oxide and the 

 salt, previously in fine powder. Mix intimately so as to 

 form a thin paste, which dry up and pulverize finely. 

 Introduce the powder into a platinum crucible, (which may 

 be filled, as there is neither melting nor frothing), and 

 expose the whole for half an hour to a very low red heat. 

 By this the production of the green manganate of potash 

 which had taken place to a considerable extent during the 

 exsiccation, is completed; while any hyper-chlorate of 

 potash which may have been formed is destroyed. 



The green mass, a mixture of manganate of potash and 

 chloride of potassium, is easily detached from the crucible. 

 It is to be dissolved in a very large quantity of hot water, 

 and when the solution has acquired a pure red colour, it is 

 to be decanted from the hydrated binoxide, the formation 

 of which accompanies the change of manganate into hyper- 

 manganate of potash. The clear solution, evaporated 

 rapidly until crystals appear, deposits on cooling a number 

 of small crystals nearly black. These are to be washed 

 with a little cold water, dissolved in a small quantity of 

 hot water, and this solution, on cooling, yields crystals of 

 the hyper-manganate of potash, chemically pure, and often 

 -\ of an inch long. They have a fine bronze colour, and 

 metallic lustre, and their solution in water possesses the 

 most superb purple colour. I have always obtained, by 



