10 Dr. Thomas Thomson [July 



3. The urine thus freed from lime was mixed with a little 

 nitrate of barytes dissolved in water ; the sulphate of barytes, 

 which precipitated being collected, washed and ignited, 

 weighed 1*3949 grains = 0*481 grains of sulphuric acid. 



4. The urine thus freed from phosphoric and sulphuric 

 acids, was mixed with a little carbonate of ammonia to 

 throw down any excess of lime or barytes that might 

 have been added in the preceding steps of the analysis. 

 The sediment vras allow^ed to subside and the urine drawn 

 off by a sucker, and the w^ashings of the sediment being 

 added to the original liquid, the vrhole was exactly neutra- 

 lized by nitric acid. Nitrate of silver was now dropt into 

 it as long as chloride of silver continued to precipitate. 

 This precipitate after being well washed was digested in 

 dilute nitric acid and then dried and fused. It weighed 

 23*449 grains = 5'782 grains of chlorine. 



5. To the whole urine thus deprived of phosphoric, sul- 

 phuric, and muriatic acids, such a quantity of sulphuric 

 acid was added as was more than sufficient to neutralize all 

 the bases, and consequently to displace all the nitric acid 

 with which they were in combination. The whole was now 

 evaporated to dryness, and the residue ignited in an open 

 platinum crucible. A white salt remained which could 

 only be a mixture of sulphate of potash and sulphate of 

 soda. It weighed 14*1326 grains. 



This salt being dissolved in water, the sulphuric acid 

 was thrown down by chloride of barium. The sulphate of 

 barytes being collected, washed and ignited, weighed 21*667 

 grains = 7*4716 grains of sulphuric acid. 



Any excess of barytes was separated by means of sulphuric 

 acid very cautiously added, and the liquid being evaporated 

 left a salt, which, after ignition, weighed 11*634 grains. 

 It consisted of a mixture of chlorides of potassium and 

 sodium. The chlorine just replaced the sulphuric acid, 

 and 7*4716 sulphuric acid are equivalent to 6*4677 chlorine. 

 Now, to find the weight of potash and soda, in these salts 

 we have the following data : 



Weight of the sulphates . . . .14*1326 

 ,, sulphuric acid .... 7*4716 



Weight of the potash and soda . . 6*6610 



