SOO Mr. Schweitzer on an Analysis of the 



ring the progress of the examination. It is indeed, under all 

 circumstances; a very safe and necessary proceeding, to ascer- 

 tain the weight of all the solid ingredients, and also the weight 

 of some of the electro-negative substances, such as sulphuric 

 acid, chlorine, &c. This will give a proper control for those 

 results which are afterwards obtained from the evaporated 

 water. For this purpose, 



1. Four troy ounces ( = 1920 grs.) of the water were super- 

 saturated with hydrochloric acid, and, when boiling*, precipi- 

 tated by chloride of barium. 



a. Experiment gave 3*622 grs. of sulphate of barytes. 



b 3-602 grs 



The average = 3-612 grs., making for 16 troy ozs. of water 

 14'448 grs. 



2. Four troy ounces of the water acidulated by nitric acid 

 gave a precipitate with nitrate of silver, weighing — 



a. Experiment 10-030 grs. 



b. ... 10-077 grs. 



The average =10-053 grs. 



This precipitate however had been influenced by the organic 

 matter, but this will be noticed again hereafter. 



3. To ascertain the total amount of the solid ingredients, 

 1000 grs. were evaporated in a platina crucible, the residue 

 dried at various temperatures, and the weight taken, when 

 no further diminution was perceptible. I'he heated crucible 

 was cooled over sulphuric acid, and then quickly weighed ; a 

 proceeding followed throughout the course of the analysis. 

 The results were as follows: — 



a. Residuet dried at 212° Fahr. gave 3*712 grs. 



b. ... dried at 300° to 310° Fahr. gave 3-311 grs. 



c. ... heated over a spirit-lamp till the evaporation of 

 the ammonia had ceased, and as long as the escape of hydro- 

 chloric acid was perceptible, gave 2-339 grs.; from the charring 

 of the organic matter the mass appeared black. 



d. Residue heated to incandescence until the organic matter 

 had been burned away, leaving the residue almost white, gave 

 2-123 grs. 



From the above statement it is obvious that a very exact 

 result cannot be obtained regarding the amount of the solid 

 ingredients. The earthy chlorides require for their existence 



* It facilitates very much the separation and lixiviation of the sulphate of 

 barytes, when it is precipitated from a boiling menstruum, and the parti- 

 cles are thereby prevented from penetrating the pores of the filter. 



t This residue when placed in a humid atmosphere attracted water and 

 became half-fluid. 



