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Mineralogical Notices. 205 



this species, and in accounting for their similarity of crystalli- 

 zation, deduces as follows their atomic volumes. — (Pogg. Ann., 

 Ixxxi, 31.) 



Formulas of Tourmaline. Mean atorn. vol. 



L S5(Si^ iB°-)+.sK(Si, B) - - - 1808 



II. S3(SiMB=)+4K(Si, B) - - - 2217 



III. Ss{Si=, iB^)+6B(Si, B) - - - 3013 



•• IV. S(Si, iB)4-3S(Si, B) - - - 1464 



V. K(Si, B)-f 4fi(Si, B) - - - 1850 



, He then observes that the numbers 1464, 1808, 1850, 2217, 

 3013, have the relation (correcting his 1-25, by substituting 1-26) 



or very closely 



1:1-24: 1-26: 1-51: 2 06, 



l:li:U:2 = 4:5:6:8. 



But let us now divide these numbers by the number of atoms 

 of the elements, and we shall find the atomic voUimeSj as thus 

 deduced, very closely equal. 







No. 



of aiorns. 



Atomic vol, 



-I- No. of atoms. 



Atomic vol. 



deduced. 



Formula 



I 





41* 



1808 — 41 



— 44-1 



u 



II. 





50 



2217 -^ 50 : 



— 44-34 



u 



Ill 





63 



3013 -f- 68 : 



= 44-31 



u 



IV, 





S3 



1464 H- 33 : 



= 44-36 



u 



V. 





52 



1850^42 : 



— 44-05 



This equality is certainly very remarkable, and the identity of 

 crystaUization is attributed to it with good reason. 



We also remark that the number of atoms 33, 41, 42, 50, 68, 

 have to one another the ratios 



1:124:127:1-51:206, 



which are coincident, as will be observed, with the ratios obtained 

 by Rammelsberg for the atomic volumes. The ratios 4:5:6:8, 



if the number of 



fact therefi 



Art. XXIV. — Mineralos'ical Notices. No. III. 



1. New Species. 



Gurolite, a new mineral ; T. Anderson, (Phil, Mag. [4j, i, 111.) 

 Occurs on Skye, at Storr, nine miles from Portree, in basalt ; it is 

 associated with apophyllite, stilbite and laumonite, though found 

 ni the finest specimens where these minerals do not abound. The 

 name g-wro/iVe (more correctly ^2/^o^27e,) alludes to the spherical 



* In the first formula, S' contains 6 atoms or molecules ; Si^ 8 ; SS, 15 ; 8Si 12 ; 

 making in all 41. 



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