50 REPORT—1858. 
It is composed of small crystals of an emerald-green colour, mingled with white 
crystals forming mammillated concretions, cementing fragments of a quartzose grit. 
In other instances, the mineral forms the cement of a conglomerate of a black 
chert-like variety of jasper. 
It exhibits slight pyro-electric properties. At 100°C. it loses a part of its water. 
Its analysis gave— 
Wiaterince cos eee hee siseeinns a Soren POD 
AITAIN ALES HA ars eeieer nisl Habel bea Bhs fa ese 36°160 
Ppmoxige Of ArOM ay ais siattave caer = ele Prema (cto v2? 
Phosphoric acid «2.0.2 0 .se.ceeee sine ae -. 30°881 
Silica ..... Ree eaten lees ye roa SURES 3-615 
Oxide fof nickel iva sieye'e, $b 'v%-0's wo’ sje); 2 Sieak 325 
Phosphate of lime (apatite) ........+--. 1°578 
Fluorine ......625. a age ied oda flier Gabi) meet Ce 
Qa E a TS RS STN as os od Soe be ohn aire ab 1-003 
98:939 
Hence the formula 5 { ar re } 3P0°+18HO may be deduced. 
Hermann considers Fischerite to be 2Al? O®, PO°+8HO, and the Peganite of 
Breithaupt as only differing from it in containing six equivalents of water. The 
colour of this last is due to oxide of copper, but in the present case oxide of nickel is 
the source. Five equivalents of the Irish mineral, plus one equivalent of Al? O°, will 
be equal to three equivalents of Peganite. 
The author only proposes this formula as an expression ofa single analysis; but as 
a great many phosphates of alumina have hitherto been confounded with Wavellite, 
he is of opinion that a complete examination of the whole series would be a desi- 
deratum. 
A conglomerate of quartz cemented by white Wavellite was also found at some 
distance from the first specimen. 
It is worthy of observation, that nearly all the varieties of the mineral are to be 
found in this carboniferous locality ; and as many of these appear to be of very recent 
origin, it is possible that some phosphatic deposits may exist in the locality. 
On Electrical Discharges as observed in highly rarefied Carbonic Acid in 
contact with Potash. By J. P. Gassior, V.P.R.S. 
The author exhibited a tube in which was placed a piece of caustic potash, and 
explained that the tube had been previously charged with carbonic acid, and after 
being exhausted, had been hermetically sealed. The small residuum of carbonic acid 
was therefore in contact with potash. This tube, when cold, showed the stratified 
discharge; but on melting the potash, the discharge merely passed in the form of a 
waye without stratifications from one terminal to the potash, and from the potash to 
the other terminal. As the potash cooled, the discharge reassumed its original 
appearance. 
On reciprocal Decomposition between Salts and their Acid Solvents. 
By J. H. Grapstone, Ph.D. PRS. 
It has been recently shown, that when two salts MR and M'R’ are mixed in solu- 
tion, a partial interchange of their component parts ensues, with the production of 
amounts of MR! and M'R, depending among other circumstances on the relative 
quantities of the original salts. L[f to such a mixture in solution, an additional amount 
of either MR! or M’R be added, it will alter the state of equilibrium, and itself suffer 
reciprocal decomposition, producing an additional amount of both MR and M’R! in 
equivalent proportions. An acid, that is a hydrogen compound, HR, comports itself 
in such circumstances in the same way as a metallic salt. Hence it may be antici- 
pated that when a salt MR’ which is insoluble in water is dissolved in some aqueous 
acid, reciprocal decomposition will also ensue, and the addition of either MR or HR! 
to the solution will cause a precipitate of the original insoluble salt MR’. The author 
had already adduced instances, in the Quarterly Journal of the Chemical Society, in 
