48 Sir Edward Ffrench Bromhead's Remarks on 



Doubtless the true composition is 



4? atoms carbonate of barytes, 

 4 atoms carbonate of lime, 

 1 atom carbonate of manganese and iron. 

 Thus it appears that neither Mr. Johnston nor myself had 

 given a correct analysis of the mineral. It is a triple instead 

 of a double salt. I failed in discovering the manganese, in 

 consequence of having neglected to examine the calcareous 

 residue : Mr. Johnston failed in consequence of dissolving the 

 mineral in muriatic instead of nitric acid. This last acid 

 should always be used in examining the earthy carbonates, 

 because it enables us to see by the colour when any iron or 

 manganese is present. 



A name derived from the constituents of so complicated a 

 mineral would be unwieldy. Perhaps the term bromlite, de- 

 rived from its best known locality, would be as unexception- 

 able as any. I am, &c, 



Thomas Thomson. 

 Glasgow, June 3, 1837. 



X. Remarks on the present State of Botanical Classification, 

 By Sir Edw. Ff. Bromhead, Bart., M.A., F.R.S.L.8>E* 



FT seems to be agreed among botanists that the natural fa- 

 ■*■ miiies must be arranged upon some new system ; and it is 

 also understood that the first attempt must consist in forming 

 natural alliances or assemblages of such as are in immediate 

 undisputed affinity with each other. Each family must be 

 related to every other family within the alliance, and I have 

 elsewhere explained the artifice by which a first approxima- 

 tion may be made. 



The question of linear arrangement is not necessarily con- 

 nected with this stage of the inquiry ; if such be the order of 

 nature, the primary alliances will throw themselves into se- 

 quence almost spontaneously ; if not, some other principle will 

 shortly show itself. In the mean time, to give the future re- 

 sult fair play, we should endeavour to place the families within 

 our alliances in their natural order of transition, as we endea- 

 vour to arrange genera within families and species within ge- 

 nera. The tendency to circulation will no doubt always offer 

 difficulties ; it would almost seem as if the progress of deve- 

 lopment were represented by a thread wound spirally round a 

 rod, on which the point immediately above another appears 



* Communicated by the Author 



