Maryland Geological Survey 115 



sediments by the relative settling velocities of their constituents, which is 

 the significant factor in sedimentation, and, on account of the time allowed 

 for working over the material in the elutriator, tends to classify them very 

 successfully. Its defect is the great amount of distilled water, time, and 

 attention it requires. The method of determining surface by heat of 

 moistening or hygroscopicity seems to have the defect that it gives only a 

 single value for each sample, so that sediments made up of very different 

 proportions of the various sizes might yet give the same results. It is 

 really a method that has much more significance for soils, for which it was 

 devised, than for sediments to which it has, however, been very recently 

 applied. 1 



The method here followed, which is that of Thoulet with some modifi- 

 cations as will be noted, is essentially as follows : A large portion of the 

 sample is first passed through sieves with respectively 3, 6, and 10 meshes 

 to the inch, and the portion retained is classed as gravel, though con- 

 cretions of these sizes should of course be separately considered. As a 

 matter of fact, none of the samples contained any gravel that would not 

 pass the 3-mesh sieve; very few, indeed, any gravel at all, and then only 

 very little. As the material was dried at 105° it was necessary to know the 

 proportion of gravel in such dried material, but it would not have been 

 pratical to dry the large portion required for gravel determination. The 

 whole lot was therefore weighed merely air-dried, and at the same time 

 a small portion weighed separately, dried for about eight hours at 105° C, 

 and the percentage loss in drying determined. This loss was then applied 

 to I he large lot in which the gravel had been determined. For the rest 

 of the analysis about 10 gm. of the sample, if necessary crushed some- 

 what in order to facilitate drying, is dried for about eight hours at a 

 temperature maintained as nearly as possible at 105°. The sample was 

 cooled in a dessicator and weighed rapidly; but the avidity with which 

 the dried samples took up moisture gave an accuracy of not more than 

 5 mg. to 10 mg. The balance, moreover, that was used for the later 



1 Kiippers, E., Physikalische u. mineralogisch-geologische Untersuchung von 

 Bodenproben aus Ost- u. Nordsee. Wiss. Meeresuntersuch. Herausgegeb. v. d. 

 Kommiss. z. Untersuch. d. deutsch. Meere, etc., 1908, N. F., vol. x, pp. 1-11. 



