

Reflections on some Miner alogkal Systems. 383 



work was finished, that of nature was not; and it may still 

 present some specimen which shall reveal its secret. If 

 we find that carbonated lime may be divided more than 

 once, it thence results only that we have taken for an inte- 

 gral molecule: that which we have been able to observe, but 

 not that which really exists; precisely as chemistry declared 

 that the emerald was composed of silica, alumine, iron and 

 lime, until it was discovered that what was considered only 

 as alumine contained also glucine, and that the iron was 

 combined with chromium. But for this chemistry did 

 not lose its importance. The integral molecule likewise 

 may be found different from what has been believed, if what 

 T have here observed should prove true; yet the general 

 .system of the molecule is unshaken. 



A recent analysis, however, appears to have excited much 

 interest in this point. Some of this pretended ferriferous 

 carbonated lime has been found, in which there exists 

 scarcely a trace of lime*. I readily believe it, but shall 

 not for that renounce the method. In M. Haiiy's col- 

 lection^ there is a mineral which at one end is ferriferous 

 carbonated lime, excessively yellow, containing iron, 

 striated and dividing in rhombs. In extending from this 

 end the colour fades, and the other characters which distin- 

 guish the common from the ferriferous carbonated lime 

 become weaker till they finally disappear. Whoever ex- 



* The Wernerians, however, cannot consistently avail themselves of this 

 defect, as the mineral still retains the same external characters ; it is the 

 chemists only who are entitled or qualified to decide on it, and they wili not 

 be very precipitate in pronouncing a sentence, since Mr. Davy has proved 

 that even one per cent, of oxygen can produce effects on the external 

 character of substances, which would serve the Wernerians not merely for a 

 specific but even a generic difference. Should they object to the introduction 

 of lime in the name of this mineral, they must recollect their own holzstem, 

 woodstone, or petrified wood, which they have thus denominated, and 

 made a particular species in flint genus, although they will not pretend that 

 it contains any vegetable or woody matter ; only that, like the .mineral 

 under consideration, it owes its form to that substance. Mr. Jameson, 

 indeed, makes an apology for considering a petrification (not petrefaction, as 

 he erroneously writes it, and which the learned Dr. Kidd applies to incrus- 

 tations), " a particular fossil species," by alleging " that woodstone 

 differing in its external characters from all other fossils, the justness of the 

 Wernerian method is evident." Upon this principle he should have divided 

 his species, as the colours, and even specific gravity of petrified oak, ash, &c. 

 are very different. He adds, that " it re. reives a good polish, and serves for 

 the same purposes as agate. '* I have examined many specimens of petrified 

 wood in various countries, but have never been so fortunate as to find any 

 that could be substituted for agate, or was susceptible of a polish even equal 

 to coarse marble. Surely the professor cannot have noticed such characters 

 merely to make Werner's fine chemical theory of the solution and infiltra- 

 tion of agate less fanciful, or give an example of transition from Wood to 

 ■ petrifaction agate, which is wood penetrated with se>:e r al of the fossils 

 that constitute agate ? "—Trans. 



amines 



