144 Researches on the Mineralogy of South America. 



(water being 1-000). Some insoluble rock-matter was left upon 

 dissolving in cold water, but otherwise the solution was quite 

 colourless and transparent. 



The quantitative analysis was conducted as follows : — 



114*67 grains, in water, left some reddish sand-grains, which 

 amounted to 2*35 grains or 204 per cent, after nitration. The 

 solution was divided into four parts and treated as follows : — 



A quarter gave, upon treatment with chloride of barium, 

 10*40 grains sulphate of barytes, equivalent to 12*45 per cent, 

 sulphuric acid. 



A quarter, precipitated by nitrate of silver, gave 39*42 grains 

 mixed chloride and iodide of silver. 



A quarter, supersaturated with ammonia, afforded 0*47 grain 

 alumina (with no trace of iron), or 1*63 per cent, alumina ; the 

 nitrate, treated with oxalate of ammonia, gave upon incineration 

 0*09 grain carbonate of lime, equivalent to 0*17 per cent, lime; 

 and subsequently the addition of phosphate of ammonia to the 

 filtrate precipitated phosphate of ammonia and magnesia, which 

 upon incineration yielded 1*26 pyrophosphate of magnesia, re- 

 presenting 1*81 per cent, magnesium. 



The potash- determination was effected on another portion, 

 18*03 grains, repeatedly heated to dryness with hydrochloric 

 acid, to expel all nitric acid • the sulphuric acid present was 

 then removed by an alcoholic solution of chloride of strontium, 

 and the potash determined by bichloride of platinum as usual ; 

 the metallic platinum weighed 0*19 grain, or equivalent to 0*23 

 per cent, potassium. 



To determine the iodine another portion, 29*84 grains, was 

 dissolved, and after filtration precipitated by chloride of palla- 

 dium ; 008 grain metallic palladium was obtained from igniting 

 the precipitated iodide of palladium, representing 0*19 iodine. 



The amount of iodine and potassium respectively found being 

 close upon the numbers of their combining proportions, their 

 united weights are given in the analysis as iodide of potassium. 



From the above data, the analysis when calculated will stand 

 as below : — 



Nitrate of soda . . . . 21*01 



Chloride of sodium 

 Chloride of calcium , 

 Iodide of potassium . 

 Sulphate of soda . 

 Sulphate of alumina , 

 Sulphate of magnesia 

 Insoluble 



55*27 

 0*33 

 0*87 

 4*74 

 9*81 

 5*93 

 2*04 



100-00 



