Bonnington Water, near Leith, Scotland. 301 



a small proportion of water. Experiment a gives therefore 

 a wrong result, as they still contain this water, but in de- 

 priving them of it at a higher tempeiature some hydrochloric 

 acid would be set free ; moreover, as the existence of ammonia 

 has been proved, it is impossible to dry the residue without a 

 small loss of chloride of ammonium, so that experiment h 

 must give a result too low. Yet the truth of the result must 

 lie within the limits of the experiments a and b. The last 

 two experiments, c and d, from the destruction of organic 

 matter, and the evolution of ammonia and hydrochloric acid, 

 can be no guide whatever. An excellent control, which I 

 frequently apply in various analyses, is to change the chlo- 

 rides, carbonates, &c. into sulphates ; the total amount of 

 the latter must closely approach the amount of the various 

 ingredients obtained by analysis when computed as sulphates. 

 This is a very satisfactory proceeding, and must give a cor- 

 rect result if the water does not contain ammonia, oxide of 

 iron or alumina ; the ammonia, however, being dissipated by 

 heat must be deducted from the total amount of ingredients 

 obtained by analysis, and as the oxide of iron and alumina 

 (both losing a large quantity of sulphuric acid during igni- 

 tion) are generally present in very small quantities, they will 

 still allow of the above proceedings; but should they amount 

 to any considerable quantity, as in some chalybeate and alu- 

 minous waters, this mode of control is not applicable. The 

 residue which was derived from experiment 3 d, amounting 

 to 2" 123 grs., was heated in a platina crucible with a sufficient 

 quantity of sulphuric acid and ignited at a red heat, until all 

 the ingredients were changed into neutral sulphates ; it yielded 

 2-663 grs. 



After these preliminary examinations the quantitative ana- 

 lysis was perfomed. 



76'800 grs. were evaporated in a porcelain basin * with a 

 proportionate quantity of chemically pure carbonate of soda, 

 sufficient to decompose the earthy chlorides and sulphates. 

 The application of carbonate of soda, besides preventing the 

 escape of hydrochloric acid, affiards another advantage, namely, 

 it counteracts the formation of sulphate of lime, which is a 

 very troublesome ingredient, inasmuch as it adheres closely to 

 the vessel, and small quantities are not easily visible in a white 

 porcelain basin ; moreover, it is not soluble in hydrochloric 



* Tlie dark brown flakes which were floating in the water were collected 

 and analysed by themselves, with the rinsing obtained from the glass bottles 

 by hydrochloric acid, any oxide of iron that might adhere to the sides of 

 the bottles being thus dissolved. The water contained only a small pro- 

 portion of iron in solution. 



