CALCAREOUS MANURES— APPENDIX. 



221 



accuracy and fidelity. For these reasons, I engaged the valuable services 

 of Professor C. U. Shepard, for the analyses of specimens which I selected 

 from the different strata of the earth at Coggins Point, exposed in recent 

 diggings, including several which had been tried as manure and had operat- 

 ed with remarkable power and benefit. Ins report of the analyses, which 

 has been received since the preceding and subsequent portions of this article 

 wei'e written, will now be presented. It enables me to furnish more of 

 what is valuable, because more certain than every thing else I could offer, 

 or than has before been offered to the public on this subject— prominent as 

 it has been made in the reports of the geological survey of Virginia. 



New Haven, October 26, 1842. 



Dear sir — The specimens of green-sand and accompanying earths have, agreeably to 

 your request, received my particular attention ; and I now proceed to apprise you ot the 

 results at which I have arrived. 



Commencing with the mechanical analysis of the green-sand, I was not a little sur- 

 prised to find that the green particles, when cleared by washing of a slight investment of 

 clay, assumed the aspect of chlorite and green earth, and more rarely of grains of ser- 

 pentine and fine scales of mica. The other ingredients of the earth were chiefly grains 

 of quartz, (some of which were penetrated by chlorite,) and more rarely specks of gar- 

 net, iron pyrites, and what appeared to be yellow phosphate of lime. Fragments of 

 shells, in a very decayed state, occur disseminated through the earth; and 1 detected 

 also small teeth and bones of fishes. The proportions^ of the leading ingredients are 

 very difficult to establish with precision ; and alter all my examinations I can only give 

 them approximaiively and within wide limits. Thus, the quartz grains may be said to 

 constitute from 60 to 80 per cent., the chloritic and micaceous grains from 10 to 15 per 

 cent., and the fine clay from 3 to 5 per cent. . - 



Nothing is plainer than that the green particles possess the chaiacter here attributed to 

 them ; since they put on all the properties so common to chlorite, being sometimes in 

 regular hexagonal plates, though usually in little granules made up of impalpable grains, 

 which under the pestle easily separate, with an oily feel, into l)right green specks. Sub- 

 jected to acids and heat, it agrees with true chlorite. 



The existence of such a mineral in the present formation offers nothing remarkable in 

 a geological point of view, since it may have originated in the decomposition of chlorite 

 slate rocks, or of veins in primitive rocks, (in which chlorite often abounds,) and in both 

 cases iron pyrites is its common attendant. Besides, it may have been derived from the 

 metamorphosis of pyroxene, or from am3'gdaloidal traps, a source of green earth very 

 often recognized in Europe and America. Indeed, chlorite (which is but another name 

 for green talc) is often interchanged for mica as an ingredient of primitive rocks, and is 

 every where little prone to decomposition, being, on the whole, one of the most persist- 

 ent of the simple minerals. 



Neither can it be objected that its chemical constitution is incompatible with the re- 

 sults obtained for green earth ; for hers we must bear in mind, also, that it is impossible 

 accurately to separate the green particles from the mica, serpentine and other ingredients 

 with W'hich they are associated'. 



M. Berthier found the following composition in 'the green grains from the green sand 

 of Havre (France) — 



Silica - - - - - .50.00 



Protoxide of iron - - - 21.00 



Alumina ... - - 7.00 



Potassa .... 10.00 



Alumina ... - - 11.00 



■99.00' 



Mr. Seybert found in that of New Jersey — 



Silica . . - - - 49.83 



Alumina .... 6.00 



Magnesia - - - - 1.83 



Potassa - - • - It). 12 



Water - - - - . - 9.80 



Protoxide of iron - - - 21.53 



Loss 89 



lOO.OOi 



* Geological Manual, by H. T. de la Beche, Pbila., 1832, p. 255. 

 t American Journal of Science, vol. xvii., p. 277. 



28 



