1867.1 Chemical Science, 567 



Mr. Walter Weldon read a paper " On the Eegene ration of 

 Oxide of Manganese in Chlorine Stills." 



The author stated that the essential features of the process con- 

 sisted, firstly, in the use of an artificial oxide of manganese, capable 

 of liberating from a given quantity of hydrochloric acid about twice 

 as much chlorine as could practically be obtained therefrom by 

 means of a 70 per cent, native oxide; and, secondly, in a simple 

 method of reproducing the artificial oxide from the " still-liquor." 

 This recovery of the artificial oxide might be performed in the stills 

 themselves, so that a charge of manganese, once placed in a still, 

 might always remain therein, continually generating chlorine ; and 

 not only never requiring removal, but never undergoing diminution 

 of in'operties, nor suffering loss by waste. 



On Friday the following papers were read, " On the Present 

 Use of Lichens as Dye Stuffs," by Lauder Lindsay ; " On the 

 Determination of Nitrogenous Organic Matters in Water," by 

 Dougald Campbell. The latter paper proved that the method of 

 estimating the amount of nitrogenous matter in water proposed by 

 Messrs. Wanklyn, Chapman, and Smith, was erroneous. " A descrip- 

 tion of a new Ether Anemometer," by Alfred E. Fletcher, Government 

 Inspector of Alkali Works for the western districts. The construc- 

 tion of this apparatus is based on the fact that a current of air 

 passing across the open end of a straight tube causes a partial 

 vacuum in it. An application of this principle is seen in a small toy 

 in common use, in which a liquid is made to ascend several inches 

 in a vertical tube, by blowing through another tube across its open 

 end. It rises by virtue of the partial vacuum caused by the current 

 of air .which crosses it. By the aid of this Anemometer the speed 

 of any current of air in flues or chimneys can be measured by 

 simply boring a hole one inch diameter through the brickwork, and 

 inserting two tubes, one with a bent, the other with a plain straight 

 end as already described, and making the necessary observation of 

 the floats ; and in this operation neither soot, heat, nor corrosive 

 vapours can prove any hindrance. So sensitive is the apparatus 

 that on a windy day the effect of each successive gust of wind is 

 observable, as it causes variations in the draught of the chimney. 

 The instrument may be used as a wind gauge by fixing through 

 the roof of an observatory a small vertical pipe, presenting a plain 

 open end to the wind. The lower end of this pipe brought down 

 into the observatory and connected with the ether manometer 

 would communicate the varying pressures due to the varying speed 

 of the wind. 



On " An Apparatus for indicating the Presence and Amount of 

 Fire Damp in Mines," by George F. Ansell. The idea embodied 

 in the apparatus was founded on the law of diffusion announced by 



VOL. iv. 2 p 



