TRANSACTIONS OF THE SECTIONS. 59 
Remarks on the Solubility of Salts at high temperatures, and on the action of 
Saline Solutions on Silicates under the influence of Heat and Pressure. By 
Professor W. K. Suttivan, PA.D., MARIA. 
The author observed, that crystallized gypsum heated with water in a sealed tube to 
a temperature of 150° Cent. lost part of its water, and formed the hydrate 2(CaO SO8), 
HO; when heated for several hours at a temperature of 200° C, it was completely 
dehydrated. Several of the zeolites, heated under similar circumstances, were also 
dehydrated, but this required a much higher temperature, and a much longer expo- 
sure to the heat than the dehydration of the gypsum. Some experiments upon the 
solubility of salts at high temperatures were also mentioned, and a suggestion made 
as to the probability that there exists for each salt a temperature of absolute insolu- 
bility, unless it was a compound decomposable at a much lower degree. In connexion 
with this subject, the author confirmed the interesting observation of M. Cousté, of the 
total insolubility of sulphate of lime at a temperature of about 150° C. The author 
stated that he was still engaged with experiments upon this subject. 
On the Composition of Norwegian Apatite. By Professor VorLcKEr, F.C.S. 
The author stated that all the specimens of apatite which he obtained from 
Kragerée in Norway, were perfectly free from fluorine and contained variable quan- 
tities of chloride of calcium. 
Tn some specimens he found as little as 1°61 to 1-71 per cent. of chloride of cal- 
cium, in others as much as 6°41 to 6:70. 
These specimens were obtained from the same block of crystalline apatite. The 
following analyses express the composition of several specimens of this Norwegian 
apatite :— 
Lie II. 
Red. Apatite. 
Hygroscopic water . . . ......, 43 43 
Water ofcombination . ....... 40 “40 
Phosphoric acid . . . . « ~ « « « « 41°88 41°74 
Dims aivahaiipenratiaeieon (oes ao eared 54°12 
Chloride ofcaleium . . . .. +... . I6i1 1°61 
IVES Apa faire eye a gleaned hg te. crit nal gag 20 
Phosphate of iron andalumina. . ... . 166 45 
, Insoluble siliceous matter . . .. =... 41°24 97 
4 Alkalies Ty CRRA Mee ARC any Opn oe ee eer ee eee *30 
99°67 100°22 
White Apatite. 
I. Il. 
Hygroscopic water sete c 19 "298 
Water of combination . . - : 23 “198 
Phosphoric acid’) 2. tite. we ee aS 42°28 
rareuwn st, Sd. 1 abe cae «eee BOG 2 53°35 
Chloride of calcium . . . . Su cee to vend AN 2:16 
Oxide of iron . sb Rei RAGA “aint Wels ‘ts +29 192 
PM MAIMGI LS) Cai. 2 Se eRe Nl DNR SL, betes at 
BUEACHAE RIA Nin: s,s) ci teh (Reh ey eect she) aon ner 
atasi sss) se ye me sty A sine Bina) aye 04 
Soda . abreast SPE Svche: sr lbtede apie ct 13 
Insoluble siliceous matter . . . . ... "82 ‘99 
100°36 100-196 
All the pie of apatite were perfectly free from carbonates, After uniting the 
phosphoric acid with lime to tribasic phosphate, and with chlorine, there remains over 
in each analysis an appreciable quantity of lime, which is neither united with carbonic 
acid nor with fluorine. At any rate, the author's results show that the ordinary 
formula for apatite cannot be applied to the apatite from Kragerie, which, as has been 
‘stated, is distinguished by the entire absence of fluorine, and a very small proportion 
of chlorine in some specimens, 
