Mr. J. D. Smith on the Hydrates of Barytes and Strontia. 87 



third book of the Mecanique Celeste) applies only to spheroids 

 in which the elevation of the spheroid above the sphere 

 (y(9, \I/)) is expressed by a rational function of cos 6, sin 9 

 cos vf/j sin 9 sin 4/."* 



June 27, 1836. DiSJOTA. 



XVIII. On the Hydrates of Barytes and Strontia. 

 By Mr. J. D. Smith. 



To Richard Phillips, Esq., F.R.S., ^r. 

 My dear Sin, 

 "tTAVING accidentally obtained from their respective solu- 

 ■*--■• tions some fine crystals of barytes and strontia, I resolved 

 to submit to experiment the various hydrates of these sub- 

 stances described by Dr. Dalton in his Chemical Philosophy, 

 in order to ascertain whether mistakes, similar to those you 

 pointed out some months since in the composition of the cry- 

 stallized hydrates, had not occurred with respect to the re- 

 mainder : in the course of which I endeavoured to verify the 

 results at which you arrived in your paper in the Phil. Mag. 

 of January 1835; but I found that the composition assigned 

 by you to these hydrates did not agree with my experiments, 

 as will presently be seen. 



The crystals of barytes were obtained perfectly dry, by 

 placing them in a funnel, suffering them to drain, and then 

 wrapping them in several folds of filtering paper, thus ex- 

 cluding them from the air, by exposure to which they speedily 

 eflfloresce, and are converted into carbonate of barytes. 



Three analyses were made by dissolving the crystals in hot 

 water, precipitating the barytes by dilute sulphuric acid, and 

 collecting and igniting the precipitate. In the first experi- 

 ment 30 grs. of the crystals gave 22-45 grs. of sulphate 

 = 14*7 grs. of barytes ; in the second, from 38 grs. of the cry- 

 stals 27*89 of sulphate = 18-3 grs. of barytes were obtained; 

 and the third afforded 27'77 grs. of sulphate = 18-2 gr. 

 of barytes from 38*2 grs. of the crystallized hydrate. Now, 



Bar. Water. 



Istexp. 14-7 -30- = 15-3"^ 



'indexp. 18-3 — 38- = 19-7 > = 51*2 of barytes combined 

 3rd exp. 18-2 — 38-2 = 20*0 J with 55-0 of water, or 76 



of barytes, or 1 eq. and 81 '6 or 

 almost exactly 9 eqs. of water. 



The (juantity of sulphate of barytes obtained in your ex- 



* Transactions of the Cambridge Philosophical Society for 1826 (vol.- ii. 



p.SBii.). 



