Malyfn of Experiments with Sulphate ef Strentiaity &e. 37 



about three months fince, by Mr. Deriabin (infpeftor of the Ruffian mines), who wfas immedi- 

 ately ftruck with its refemblance to a fubftance of the fame nature found in Penfylvania. 



The cryftallization of the middle vein is either that of bevilled tables, or rhomboidal cubes 

 of nearly an inch in diameter ; the tranfparency of the latter exceeds that of every other fpe- 

 cies ; the fpecific gravity of the cubes varied from 3,88 to 3,96, while tl\at of the fibrous was 

 about 3,91. 



Wifhing to obtain feme muriate of barites, about nine months fince, I reduced a portion of 

 thefpar to the ftatc of a fulphure, and diflolved the earth in marine acid; the great folubility of 

 the fait, with its needle-formed cryftals, foon indicated the prefence of ftrontian. 



Several trials which were then made with it, fully confirmed the refult of the firft experi- 

 ment. Shortly after this, Dr. Beddoes informed me of his having met with a paper of Klap- 

 roth's, containing an analyfis of the American fulphate. 



Since the firft difcovery of this rare produdion, Mr. Bright has furniflied me with fpeclmens 

 of another variety from the neighbourhood of Ham-green, where it is found breaking through 

 the foil in fuch large maffes that it has been made ufe of in mending the roads. The cry- 

 ftallization of the latter, like that of the Redland, confifts of bevilled tables ; it does not, how- 

 ever, partake either of its tinge, or femi-tranfparency : its fpecific gravity is betwee n 3,60 

 and 3,68. 



The prefcnt ftate of the arts furnifhes continual inftances of the refufe of one manufadure 

 forming the bafis of a fecond. While this continues to take place, it is evident that every 

 mere produftion muft claim a full inveftigation. The peculiar properties of^this earth renders 

 it probable, that its affinities may fhortly be made to furnifh us with thofe produ£tions from 

 the raw materials of our own Ifland, which we can now only obtain with confiderable diffi- 

 culty from other countries. 



The following analyfis was undertaken at the folicitation of fome chemical friends ; more 

 leifure would doubtlcfs have contributed to greater accuracy. What is now ftated is the 

 mean refult of feveral experiments, the differences of which have rarely amounted to more than 

 two or three grains. Confidering the fibrous variety as the moft deferving attention, it was 

 the firft fubjectcd to analyfis. 



To find whethA it contained any portion of water, or other volatile material, 500 grains 

 were expofed to a red heat under a muffle : the lofs, amounting to no more than four grains, 

 proves than the quantity of water, if any, muft have been very trifling. 



1. 200 grains of the powdered fpar, in its original ftate, were digefted with a folution of 

 carbonate of pot-afh (obtained by deflagrating nitre and tertar) ; the powder, when dried in a- 

 red heat, weighed 163,5 grains. 



2. A folution of this powder in diluted marine acid extricated 47 grains of carbonic acid, 

 leaving about one grain undifToIved : this was afterwards taken up by the alternate application 

 of carbonate of pot-afti and marine acid. From this it appears that the whole quantity of 

 earth muft have been very nearly 1 16,5 grains. 



3. The folution, No. 2, was then fully charged with cauflic ammoniacal gas, which pro- 

 duced fcarcely any traces of precipitation ; the addition of carbonate of ammonia immediately 

 threw down a precipitate, which, dried as before, weighed nearly 160 grains, the difference 



in 



