310 



Intelligence and Miscellaneous Articles, 



rine, iodine and bromine, of being like them an eAergetiq o^iz^ffn; 

 — Journ. de Pharm. et de Ch., Juin 1845.,io imii Mitnimocasb svad 



PHOSPHORIC ACID FOUND IN ALMOST ALL ROCKS*. i[«<! 



The following extracts from a lecture by Dr. R. D. Thomson in ■ 

 the forthcopaing number of the Quarterly Agricultural Journal of 

 Scotland, taken in conjunction with the paper printed in the Philo- 

 sophical Magazine on the Inorganic Constituents of Lichens, render 

 it obvious that few rocks will be found destitute of phosphoric aoidfi i 

 ' ■ ''iUifknq 



Greywacke Soil. — By explaining geologically the dependence of' 

 the soil upon rocks, and tracing the production of various soils from 

 their respective rocks, not only may much interest, but much instruc- 

 tion be derived in the chemical studies of the agriculturist. During 

 the last winter many careful analyses of rocks have been made. 

 These I do not intend to describe at present ; but, as an example of 

 the importance of such analyses, I may notice those of the greywacke 

 and the superimposed soil at Balkerr in Wigtonshire. The experi- 

 ments were conducted by my pupil, Mr. James M'Bryde, under my 

 immediate direction. The analyses of the rock and soil are placed 

 in parallel columns for the -sake of comparison. Specific gravity 6f 

 the rock 2-76. 



Decomposed soil. 



Fibre , 



Organic matter and 

 some water of un- 

 decomposed soil 



Phosphate of iron ... 



Peroxide of iron 



Carbonate of lime ... 



Magnesia 



Chloride of sodium \ 



Sulphate of lime ... / 



Soil. 



1-01 



12-51 



2-49 

 7-60 



•74 

 1-72 



005 



Greywacke. 



0-94 

 9-94 



trace. 



Partially iindeeom- 

 posed soil. 



Gravel 



Stones 



Silica 



Alumina 



Magnesia 



Lime 



Potash and soda 

 Water , 



lilfiKj If;'-)i^(,ploo 



Soil. 



6-39 

 19-16 

 38-79 

 8-30 

 0-69 

 0-55 



Greywacke. 



72-18 

 11-68 

 2-30 

 0-96 

 0-95 

 2-40 



The important fact that phosphoric acid is contained in greywacke 

 is demonstrated by this analysis. In another examination we found 

 a somewhat larger amount, and the variation may be considerable in 

 different localities. A comparison of the preceding columns enables 

 us to deduce the effects of cultivation. It is obvious that phosphoric 

 acid and carbonate of lime have been added artificially. Phosphoric 

 acid has been long known to exist in volcanic rocks (Boussingault's 

 Economie Rurale, i. 561), and the fact has been confirmed by Mr. 

 Fownes, but I am not aware that its occurrence in primary rocks was 

 pointed out until the experiments made here in 1843, upon lichens, 

 demonstrated the fact J. I have since analysed all the primary rocks, 



* Communicated by Dr. Thomson. - - ...li. .,.-;.i^,.w 



f See also the very complete researches of Mr. Sulllvaii ori' tins Sit)^ct 

 in our last number. — Eds. '' ''' 



X See the Journal of Agriculture for January 1846, No. 8. '--^ 



