BAIRD ^T^TLOCK. (LONDON) LTD. 



DIRECTIONS FOR USE OF FRANKE'S GAS BURETTE No. 4746. 



To fill the burette allow the gas to stream freely through it for some time. If, however, there is only a small 

 quantity of gas at our disposal, it is necessary to proceed in the following manner : The burette is first completely 

 filled with water, the plug with stopcock open is then inserted and the stopcock closed. The upper end of graduated 

 part marked d is now connected with the gas source, a, b, and c are opened, and the water allowed to flow out 

 until about the point m is reached, when stopcock a is closed and the burette dipped into a cylinder of water 

 until the level of the water in and outside the burette is the same, in which position stopcock is closed. By 

 this means we have a given quantity of gas enclosed under the usual atmospheric pressure. The plug is now 

 withdrawn, the water run out of the receiver B, and is filled with potash solution, after which the plug with open 

 stopcock replaced and then closed. The receiver B must not contain the smallest air-bubble. Stopcock b is 

 now opened and the potash solution allowed to flow into a, in which it is shaken slightly and then allowed to 

 flow back to B. When all has run back stopcock b is closed, the plug withdrawn, and the solution run off. The 

 reservoir is now washed out with water, and then in the same manner completely filled with water and the plug 

 replaced. The burette is then again inserted into the cylinder of water, stopcock b opened, and at same water 

 level the number of cubic centimetres read off, which give direct the volumes per cent, of carbonic acid which 

 was contained in the analysed gas. 



If an estimation of oxygen or carbonic oxide gas is required, we manipulate in the same manner, only changing 

 the absorbing reagent. 



Respecting the carbonic oxide estimation, it is necessary to mention that the water in the graduated part 

 should be drawn off by an aspirator bottle before the absorbing reagent is run in. Then the absorbing liquid 

 (ammoniacal cuprous chloride) is admitted and shaken up with the gas. Afterwards this is drawn off as before 

 and water run in in its place, in order that the remaining trace of ammonia in the residual gas may be absorbed. 

 See Journal fur Prakiische Cliemie, Band 35, February, 1887. 



4747 (B) 



4748 



4747 s Aerorthometer, for use at gas testing stations. As prescribed by and made for the Metro- 

 politan Gas Referees (see their notification of June, 1898) . See also original article by Mr. 

 A. Vernon Harcourt, M.A., F.R.S., in the Proceedings of the Royal Society of London, 

 Vol. xxxiv., p. 166 ; Gas World, 4th June, 1898, p. 863 ; Journal of Gas Testing, 

 May, 1898, p. 1258. 



A. Price of simple aerorthometer, without stopcock 



B. Price of recording aerorthometer, with stopcock, as figured 



4748 T Lux's Gas Balance 



(Description and directions for use supplied with each balance.) 



2 10 

 3 3 



21 



(CHEMICAL AND SCIENTIFIC APPARATUS AND PURE CHEMICALS. 



