62 
( 2 .) It will be seen from the table showing the supposed 
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 203 -f-Al 203 +P 205 ) calculated from the Fe, Al, and P 2 O 5 , 
each estimated directly, is rather greater than the result 
obtained by weighing the three oxides together, the num- 
bers being 2,592 and 2,570 respectively — difference 22. 
(3.) In the determination of the alumina it was separated 
from the iron by means of tartaric acid and sulphide of 
ammonium, and weighed as AI 2 O 3 +P 2 O 5 ; the difference 
between this and the determined amount of P2O5 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 O 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 
rather varying results, comparatively, could only be obtained 
for the sodium. The above is the mean of four, of which 
the highest was 32 and the lowest 22 parts per 1,000,000, 
the reason being that the quantity of sodium present was 
only very small, so that the traces of it also contained 
in the reagents had an appreciable effect, though they were 
as pure as could be obtained. The results got for the 
potassium, however, agreed very nearly. 
(7.) The lead was determined by the method given in 
