OK THE DIOPSIPE. 15 



serving, those that appeared to them most interesting either 

 for their novelty or their rarity. The-lithology of these re- 

 gions, less assiduously cultivated than the other branches of 

 natural history, appeared to the learned academician an am- 

 ple field, in which science might promise itself a rich har- 

 vest. His expectations were not disappointed, and the re- 

 sult of his researches, the merit of which is enhanced by 

 the difficulties he had to overcome, is an account of his tra- 

 vels, the speedy appearance of which he gives us reason tq> 

 hope. In the mean time we have to express our thanks to 

 Mr. Bonvoisin for having made us acquainted with the prin- 

 cipal substances he has collected in his mineralogical tour. 

 Of these a very ample description is given in the Journal de 

 Physique for May 1806, but my attention is confined at pre- 

 sent to two of them, to which he has given the provisional 

 names of mussite and alalite. 



A few days ago I was present at a meeting, at which Mr. y wo f t h e 



Haiiy exhibited to several of his pupils the new substances, new substances 



,. , , i -i • i • r» i i_« foundbvhim 



which he purposes to describe in his course ot lectures this particularly 



year, and among others those which Mr. Bonvoisin has sent noticed, 

 from Piedmont to Mr. Fourcroy, who has destined the 

 -most remarkable for the gallery of the Museum of Natural 

 History*. Among these substances two particularly enga- 

 ged my attention, which the celebrated professor of miner- 

 alogy, informed us he had been led by his observations to 

 urtite in one species, the essential characters of which differ 

 completely from those that distinguish all the known spe- 

 cies, notwithstanding their appearance seems to indicate, that 

 they should be separated. The constant occupation, which 

 the approaching publication of the second edition of his 

 Treatise on Natural Philosophy imposes on Mr. Haiiy, not 

 allowing him to publish the results of his examination of the 

 substances in qxiestionf , I requested his permission, to take 



* Mr. Haiiy has since given a description of the diop=ide, which con- 

 stitutes the subject of the present paper, in the public lecture on miner- 

 alogy, which he gave at rhe Museum of Natural History on the jath of 

 July this year. 



•f With respect to the diopside Mr. Haiiy has followed his usual cus- 

 tom of committing to writing the new observations he delivers to his pu- 

 pils, and depositing a copy in the library of the Museum, which every 

 Diie is at liberty to transcribe after the lecture. 



this 



