BAIRD &TATLOCK (LONDON) LTD. 



The laboratory vessel D, in which all absorptions are carried out, is closed by a three-way glass tap having two horizontal 

 capillary branches. One of these leads, through the above device of steel faces and clamp, to the measuring vessel, whilst the 

 other is connected with a small water aspirator. The suction of the aspirator enables the laboratory vessel to be filled with 

 mercury at the outset of the analysis, and facilitates the cleaning of the vessel and the changing of the absorption reagent during 

 the analysis. An ordinary filter flask inserted between the aspirator and the laboratory vessel acts as a trap to receive the spent 

 reagent and any mercury which may be drawn over with it. The fresh reagent is introduced into the laboratory vessel by means 

 of a small glass pipette. The inner surface of the measuring vessel A and the barometer B are always kept wet. The moist 

 gases are measured by bringing them to a certain constant volume v (an etched line) in A, and then deducting thin pressure in 

 millimetres of mercury from the reading of the barometer B. The tension of aqueous vapour in the gases is exactly balanced 

 by the tension of the aqueous vapour in the barometer tube, and therefore the difference between the " moist vacuum " reading 

 in B and the reading when the gas is being measured corresponds to the pressure of the dry gas at the particular volume v and 

 tin- temperature of the water in the jacket. 



The whole apparatus stands on a rectangular table, about 4 ft. 6 in. by 2 ft. 6 in. The general arrangement is shown in 

 the illustration. All readings are made by means of a telescope fixed at a distance of about 3 ft. from the table, the measuring 

 vessel and barometer being illuminated by a movable artificial light at the back of the water-jacket. 



The chief advantages of the apparatus are : 



(1) That it permits of rapid and accurate working. 



(2) That only small quantities of gas need be used for a given analysis, e.g., the pressure of 5 cubic centimetres of gas is 



from 50 to 80 millimetres, according to the particular " constant volume " mark employed. 



(3) That in an " absorption " analysis the quantity of the reagent used is reduced to a minimum. 



(4) That in an " explosion " analysis the capacity of the apparatus is sufficiently large to allow of the proper degree of dilution 



of the explosive mixture (e.g., CH t + 2O 2 ) by excess of air or oxygen. This is particularly important in the analysis 

 of hydrocarbon mixtures. 



The apparatus has been installed in the research laboratories of the Manchester University, at the Listei Institute of Pre- 

 ventive Medicine, London, and at the Battersea Polytechnic, London. The apparatus at the Manchester University has been 

 used for nearly 2,000 different analyses during the past six years. 



BAIRD HTTATL.O.CIS LUNUDN 



4763 



4764 



4765 



Dittmar's Gas Analysis Apparatus. 



This apparatus, made by us to the order of several of the principal laboratories in England, is pre-eminently 

 fitted for research work and accurate investigation. 



4763 T Price as figured, complete with iron mercury trough, mahogany cased outside, and two 



absorption pipettes, Nos. 4764 and 4765 

 4764 T Pipette, modified by Lennox, mounted on mahogany stand 

 4765 T Pipette, modified by Lennox, mounted on mahogany stand . . 



11 10 

 1 15 

 1 12 



For description and method of working see " Dittmar's Quantitative Chemical Analysis," 1877, page 209. 



.CHEMICAL AND SCIENTIFIC APPARATUS AND PURE CHEMICALS- 



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