ONE OF THE TREFRIW MINERAL WATERS. 359 



ever, there is a danger of a little sulphuric acid volatilizing 

 by decomposition of the sulphate of iron ; but by careful 

 heating this may be avoided. A loss of ammonia will never- 

 theless have been incurred j but as this, together with the 

 trace of organic matter, did not amount to more than 8 to 

 10 parts per million, it was not of very much consequence. 



(2) It will be seen from the Table showing the sup- 

 posed combination of the salts, that the total bases formed 

 were rather more than sufficient to combine with the 

 acids ; and the base which is given above as uncombined 

 is alumina, as it is thought that the quantity of this body 

 obtained was rather too high; for, in addition to the total bases 

 being too large for the total acids, the sum of the oxides 

 (Fe 2 ? + Al 2 3 + P 2 5 ) calculated from the Fe, Al, and 

 P 2 5 , each estimated directly, is rather greater than the 

 result obtained by weighing the three oxides together, the 

 numbers being 2592 and 2570 respectively — difference 22. 



(3) In the determination of the alumina it was sepa- 

 rated from the iron by means of tartaric acid and sulphide 

 of ammonium, and weighed as Al 2 Oj + P 2 5 ; the dif- 

 ference between this and the determined amount of P 2 s 

 gave the quantity of alumina. 



(4) The phosphoric acid was estimated by precipitating 

 with ammonium molybdate; and as the amount was only 

 small, by weighing the precipitate obtained on a constant 

 filter, the calculation was then made from the composition 

 of the precipitate, which contains, according to various 

 authorities, 3*142 per cent. P 2 5 . 



(5) The iron was determined directly at the spring with 

 potassium permanganate, and afterwards gravimetrically in 

 the laboratory. The results obtained agreed very nearly. 



(6) Several determinations were made of the alkalies ; 

 but only rather varying results, comparatively, could be 

 obtained for the sodium. The above is the mean of four, 

 of which the highest was 32 and the lowest 22 parts per 



