462 PROFESSOR W. DITTMAR ON THE BEHAVIOUR OF THE 

 Hence by calculation — 



(1) (2) Mean. 



Carbonic acid, . 29'008 29 '004 29-006 



Oxide of potassium, 69163 69-219 69-191 



Water, by difference, . ... ... 1-803 



100-000 

 If we calculate the C0 2 as K 2 C0 3 , and the rest of the alkali as hydrate, there is a small 

 excess of water left, thus — 



Carbonate of potasb, ..... 91153 



Caustic potash, KHO, 8'389 



Water, 0-458 



100-000 

 Experiment III. — An unrecorded weight of carbonate of potash was heated in the 



platinum crucible in nitrogen for an hour and a quarter, by means of the blowpipe. 



No spongy platinum used. 



1-4516 grm. of product gave 0-4508 of C0 2 , and 1-8337 of K 2 S0 4 . Hence, by 



calculation — 



Carbonate of potash ...... 97'595 



Hydrate, KHO, 2-115 



Water, 0-290 



100-000 



Experiment IV. — An unrecorded weight of carbonate of potash was placed in a boat, 

 and heated in a muffle, within a porcelain tube, in a current of nitrogen, for two 

 hours. 



0-834 grm. of product gave 0'2645 of C0 2 and 1*055 of K 2 S0 4 ; or 



Carbonate of potash, ...... 99 - 663 



Oxide of potassium, . . . . . . 0457 



100120 



In another sample, Mr Henderson found, by means of the chloride of barium method, 

 0*49 per cent, of K 2 0. 



Experiment V. — A quantity of carbonate of potash was heated in the platinum 

 crucible in a current of dry carbonic acid, first for one hour by means of a small Bunsen 

 and then for an hour and a half with a more powerful lamp. The residue, however, was 

 not analysed, because it exhibited a brownish colour, as if the organic matter, in the 

 ignition of the bitartrate, had not been quite completely destroyed. A similar colour had 

 been noticed in the residue obtained in Experiment III., but not in that of Experiment IV., 

 although the same preparation had been used throughout. I did not think, and do not 

 now, that the remnant of organic matter (if there was any) amounted to more than a 

 minute trace ; yet to make sure that in this experiment at least there should be no 



