Analytical chemistry

1920 Journal of the Chemical Society Abstracts  
The author advocates the use of the short swing method of weighing in place of the more tedious long swing met'hod so often advocated in text-books. (C'ompt. rend. , 1920, 170, 728--731).-The construction of the nephelometer is based on the formula I / I , = 1e-B/JfP, where 1 and lo are the intensity of the transmitted and incident light respectively and M the total mass of the particle5 in suspension in the medium. The absorption of the medium is compensated by a prism of very slight angle, of
more » ... neutral tinted glass. It is shown that the displacement, x, of this prism for the compensation is a linear funct'ion of U , and consequentJy the value of izI may be read off E. H. R. A Nephelometer. direlctly oln a, scads. [Se8ei, iurthGr, J . Soc. Chem. I~c Z . ,~ 1920, 35oA.l w. G . , 1920, 45, 94-97).-The funnel containing the filter and precipitate t o be washed is supported in a ring a t one end of a counterpoised rocking arm; t'he latter is connected with a commutator to reverse a motolr actuating the valve on the water supply. When the motor is started, the valve is opened and water is admitted through a rotating jet on to the precipitate. As soon as a certain weight of water has collected in the funnel, the rocking arm is depressed, the motor is reversed, and the valve closed. As soon as a sufficient quantity of water has passed from the funnel, the rocking arm rises, the motor is thus again reversed, and water admitted to New, Simple and Rapid Process for Collecting and Charactmising the Films Produced by Metalloids and Metals capable of being Volatilised by Heat. AD. BRALY (Compt. rend., 1920, 170, 661--663).-A simple portable apparatus is desoribed for use in the field by prospectors in the examinac tion of minerals. It consists essentially of two plates of mica, suitably mounted, on one of which the mineral is heated in the blowpipe flame, the second being so adjusted as t o condense and collect the resulting volatile vapours. To the film thus obtained the usual tests, for characterising the metals present, may be applied. By suitably regulating the flame telmperature it is possible to obtain succmsive films from the different metals or metalloids present in the minerd. CHARLES CH~NEVEAU and RENB AUDUBERT Machine for Washing Precipitates. ERIC SINKINSON (Arhalyst
doi:10.1039/ca9201805327 fatcat:oo6wr4s76bgmppvxs2reos4b5i