

Prof. Mitscherlich on Crystals' formed by Heat. 129 



for his great object is to examine, with the utmost care, the 

 region which lies between Mackenzie and Coppermine rivers ; 

 and here he will unquestionably more than supply the place 

 of those collections which were lost during the former journey. 

 Captain Franklin again, and the officer that accompanies him, 

 will proceed from the mouth of the Mackenzie in boats, to 

 Behring's Straits ; they will doubtless devote as much time as 

 their other important avocations will permit, in gathering 

 plants and other objects of natural history ; and Dr. Richard- 

 son will take care to instruct one or more of the party in the 

 mode of preserving vegetable productions. The prayers and 

 the wishes of their friends, and of every friend to science, will 

 accompany these able and intrepid investigators. 



Some idea may now be formed of the extent and value of 

 the collections which will be obtained, and we are confident 

 that such arrangements will be made as will secure to every 

 botanist the credit of his respective discoveries. We think 

 then, that these should be destined for the foundation of a 

 Flora of the British Possessions in North America ; which, 

 if no individual more competent to the task presents himself, 

 the writer of the present article will not shrink from under- 

 taking ; and this he offers to do the more readily, since some 

 of the most effectual aid has already, and unsolicited, been 

 offered to him. 



Aht. XXI.— Ou the Production of Crystallized Minerals by 

 heat. By Mr. E. Mitscherlich, Professor of Chemistry 

 in the University of Berlin. 



At Fahlun and Garpenberg in Sweden, and in several of 

 the founderies of Germany, I had observed that the scoriae 

 possessed the same form, and were composed of the same 

 elements as certain minerals found in nature ; and I possess 

 at present upwards of forty different species. Among these 

 are the subsilicate of the protoxide of iron, the silicate of the 

 protoxide of iron, also that of the protoxide of iron and of 

 lime, and that of magnesia and lime. These substances, 

 when crystallized, present the form of peridot. Another 

 class of them are the bisilicatcs of protoxide of iron, of pro- 

 VOL. u. NO. I. JAN. 1S25. K 



