Organic Acids in the Examination of Minerals. 31 



tightly in the centre of the tnbe divides it into two compart- 

 ments, one of which is filled with pulverized citric acid and 

 the other with potassium nitrite, to be subsequently dissolved 

 in water obtained in the field. This simple arrangement, 

 greatly economizing space, will naturally suggest itself to all 

 working mineralogists, and would scarcely be worth mention- 

 ing were not wet analyses commonly regarded as impracticable 

 in field work. 



In proposing the use of organic acids in this connection, 

 we are aware that they already occupy a place in the lists of 

 " Special Reagents '' contained in the larger treatises on Blow- 

 pipe Analysis. Plattner* mentions tartaric acid, but limits 

 its use to the separation of yttria and zirconia (by ammonium 

 sulphide) ; and he names oxalic acid as employed in the pre- 

 cipitation of lime and in the separation of iron and uranium 

 from yttrium, cerium, and lanthanum. To remove the organic 

 acids from this restricted use, and to accord to them a more 

 important position in the list of reagents, is our aim. 



APPLICATION TO GEOLOGICAL PHENOMENA. 



24. This newly developed power of the organic acids has 

 undoubtedly an important bearing on the chemistry of geo- 

 logical changes : organic acids, resulting from the decomposi- 

 tion of vegetable and animal matter, demand recognition as 

 powerful agents in the work of disintegration and consoli- 

 dation. 



Many of the results attributed to the imperfectly studied 

 bodies, geic acid, C 30 H 13 O 7 , humic acid, O 20 H 12 O 6 , and ulmic 

 acid, C 20 H 14 O 6 t — as well as the oxidation products, crenic 

 and apocrenic acids — are perhaps the silent work of a higher 

 class of organic acids. 



That such acids constitute ingredients of the soil, is well 

 established: "When the leaves of beets, tobacco, and other 

 large-leaved plants, fall upon the soil, oxalic and malic acids 



* Plattner's Manual, translated by Prof. H. B. Cornwall, third edition, pp. 53 and 54 

 1875. 



t Mulder, Ann. Chem. Pharm., xxxvi, 243, 1840. Detmer ascribes to humie acid 

 the formula C 60 H 54 27 , and regards humic and ulmic acid as identical in composition . 

 Cf. Watts' Diet., II Suppl., 648. 



