Bulletin - United States Geological Survey Volume 32-38 (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1886 Excerpt: ... December 31... mm () 12 ni... 3a.m. 12 m... 1 About 2 mm. each. 147 158 II. 09 riso 165 I 18(1 '.;..' 170 1.1 '1 If we regard dasa function of h we find it linear in the case of white and of red bolus and quadratically retarded in the case of tripoli, but to the latter fact I would attach no significance. It may be due to the unavoidable fluctuations of temperature.1 So long as the descent is uniform (d proportional toh) the force acting ou the particle is nil. The effect of gravity is exhausted in doing work against the frictional resistance. In Table 3 are given the results obtained with fine tripoli suspended in distilled water to which various percentages (by weight) of common salt (XaCl) have been added. The precipitation tubes in this series of experiments were 3 cm. in diameter and 15 cm. long. Values for d are given only when planes of demarkation were observable. In other respects the table is like the preceding one, except that d is here expressed in millimeters. Where two sets of figures are given, two surfaces were apparent. Table 3.--Subsidence in salt solutions. The experiments show that the rate of sedimentation increases rapidly with the quantity of salt in solution; that even small quantities of salt produce very marked effects; d varies linearly with h. The absence of stratification in cases of greater rates of subsidence (solutions 1 to 15 per cent.) is confirmatory of the remarks made in au earlier paragraph (p. 16) on the rearrangement of particles according to the density of different parts of the liquid and accords well with the other views there given. The remarkably accelerated increase of rate observed on passing from fractional to integral per cents, (composition) is to be noticed. 1 See p. 20 as to convective currents ami the ch...