Chemical Examination of Natural Waters. 221 
mina and iron, with which it is thrown down on addition of 
caustic ammonia. It is certainly interesting to observe that a 
compound indispensable to the full development of the human 
frame,-should be so widely diffused as to be present, in minute 
quantity, in almost all natural waters. We are less surprised at 
this fact now than we should have been a few years ago, since 
we now know that phosphoric acid is found in granite, mica slate, 
various limestones of all formations, as well as in many simple 
_ Minerals where it had before been overlooked ; the writer has 
also detected its presence in connection with pone Sty in most re- 
cent corals and coral limestone*—and Dr. Jackson informshim that 
in the analyses of sea waters for the Exploring Expedition, he 
also detected phosphoric acid.t It is also a fact of significant in- 
terest, that silica, in its soluble modification, should ‘he found as 
an almost gan? ingredient of natural waters, 
The nitric acid was determined quantitatively, daly in one 
instance, ne its presence’ was very evident in several of these 
waters; from the rapid deflagration of the residue of evaporation, 
on ignition. It is worthy of remark. that in all cases where this 
deflagration was observed, the residue was found to be strongly 
: alkaline, and to effervesce on the addition of a dilute acid: the 
| _, Carbonate of soda and potassa being formed from the decomposi- 
tion of the nitrates and crenates of these bases. 
- Table I presents the general results of the evaporation of one 
gallon of each water: and the estimation of the quantity of car- 
bonic and sulphuric acids in the same quantity. 
ee G88 SH EE LAB oh Je 
matter in I 000 , ; fe oe 
SCA Reet 50-752 i874 = 5.770 1059597 $5 
Venne of solid in 1 gallon, 3971 2-13 15: CAR aatie 
Leaving soma 6.02 | 425 | 085 I 4-62 (50-055) 
Keaving solid matter, 33-68 | 6°66 | 1:25 4 
: a hee er share wae ‘Soluble el ards 431073 
bp bone 245 | 240 | 0-69 0 ye 
: ne a 24 | 447 | 0:56 Cenk a 
fares te 5 I 549 trace ete 
es) |10-313]17-418} 9-516 3 ; : 
Sul: acid in one gallon, > 1058 “00551 00824! 02451 (0037 “00246 4-968 
ated 
ay n give a aR ee he one acid, ab we cannot doubt do 
but in exceedingly small quantity—in sea waters. We were led to these 
examinations by the coral analyses before eo to. 
tases ‘Vol. Il, No. 5,—Sept, 1846, | 
