b for the Advancement re Science. 3 et e 
phosphoric acid. Prof. oe has shown that: traces of phosphori ae 
acid are met with in many rocks of igneous origin, but-also in sated ye 
rocks, particularly in imbeicne rocks, the presence of phosphoric acid 
has been indicated by several chemists. The author found the propor 
tion of phosphoric acid in graptolite, from the neighborhood of Ciren- ° 
cester, amounting to 0°124 per cent., equakto:0-260 of bone-earth, and — 
in Stonesfield slate from the same locality amounting to 0-117, equal to. 
244 per cent. of bone-earth. As water, charged with carbonic acid, is ¢ 
capable of seeoOe bone-earth, this important, fertilizing substance is Ss 
found in many natural waters, phosphoric 
acid. _ Such ister, therefore, may be applied with advantage for irriga- 
tio » often neglected naturalsource,. 
are strikingly enbiie? in the irrigated meadows in the neighborhood Pa. 
of Cirencester ; and it is the.opinion of the author that one of the chief 
causes of the bouskeial effecia which follow the application of the water: -. 
for irrigation in this locality, isto be found in the phosphate of lime 
it contains.. .In a tea-kettle incrustation formed in a short period by 
this water, the proportion of phosphoric acid.was found to amount to 
1:25 per cent., Showing’a considerable quantitysof this acid present in 
he water. A very hard water from Edinburgh. Rice, proved — 
tain phosphoric acid, but its proportion was not so large as that int 
Cirencester water, ‘the quantity of phosphoric acid: in a boiler ane 
a- 
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et contains phosphoric acid, but the open amounts to 
~~ mere tra _A quantitative determination of phosphoric acid in the . 
: goler cepa of a Canada steamer gave only 0-0306 per cent., and 
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The a ae of Potassium; by Mr. W, Perriz. 
While speculating on the consequences of the dynamical theory of 
heat, I was led to the conclusion that cold potassium ought to be found 
luminous ; and farther, that it ought to be only about a tenth part as lu- 
minous as phosphorus. On testing this experimentally, with the precau- 
tions for sensitive vision which the anticipated feebleness of the light 
indicated to be necessary, the result was, that on diving a bit of po- 
tassium, (which was quite dry, being protected only by coating of 
bees’ wax,) the halves showed two distinctly aes Ee 2 sections the 
light being about a tenth of that from a similar surface of phosp orus, 
as far as the eye could make the pa pe The light diminished, 
naturally, as a protecting coating of oxyd was formed, but remained 
just perceptible to the most sensitive sight, as long as half an hour. 
On the presence of Fluorine in Blood and Milk; by Dr. G. Witson. 4 
In 1846 I announced to the Royal Society of Edinburgh that after 
ding that sea spar was soluble in water, and occurred in many nat- 
waters, I thought it well to seek for it in milk and blood, and found 
net evidence of its presence in both. The proofs however were 
‘so decisive as I could have wished. This summer, however, I have 
