Chemical Examination of American Minerals. 57 



1811, as is well known to many of his friends, but without 

 being satisfied with the results, when circumstances obhged 

 him to relinquish in great measure his scientific pursuits, so 

 that he never publislied a;» account of his discovery. The 

 notes of his experiments were exhibited to me in the year 

 1820, and extracts from them were communicated to Mr. 

 Nuttall, as may be seen in Silliman's Journal, vol. vi. p. 171 . 

 Dr. Langstaff obtained as the mean of several trials, 



Silica, ------ 32 



Magnesia, - - - - - 51 



Oxide of iron, - - - - - 6 



Fluoric acid, ----- 9 



Water, ------ 2 



The quantity of fluoric acid was determined by the difi'er- 

 ence between the sum of the other constituents, and the amount 

 of mineral subjected to experiment : a very imperfect method 

 it must be confessed, but almost the only one that could at 

 that time be employed. 



The mineral soon became known to all our collectors, and 

 as it appeared to be new, Colonel Gibbs, with the consent of 

 Dr. Langstafi', proposed for it the name of Brucite. Under 

 this appellation a large quantity of it was sent to Europe. 



From some misunderstanding, it was supposed by several 

 mineralogists to be a fluate of magnesia, by which name it 

 was introduced in tlie Tabular View of the first edition of 

 Cleaveland's Mineralogy, published in 1816. The author of 

 that excellent treatise states, that he expected to have receiv- 

 ed an account of the mineral in time to insert it in the body oi 

 his work, but was disappointed. 



In Silliman's Journal for 1819, it was announced that an 

 analysis of Brucite, a new mineral, would appear in the fol- 

 lowing number. But the analysis was not, however, pub- 

 lished. 



Just before this notice appeared, and without being aware 



Vol. III. 8 



