286 



CENTRAL SCIENTIFIC CO., CHICAGO, U. 8. A. 



6824. 



6826. 

 6830. 



6832. 

 6836. 

 6838. 

 6844. 



6850. 



6851. 



I 



No. 6824. No. 6826. No. 6830. No. 6832. No. 6836. No. 6838. 



No. 6850. 

 Sectional Diagram. 



No. 6844. 



250 

 4.50 



500 

 4.80 



No. 6851. 

 No. 6850. 



GAS COLLECTING TUBES, of glass, long form, with two glass stop-cocks. 



Capacity, cc 125 



Each $4.30 



GAS COLLECTING TUBE, short form, of glass with two stop-cocks. Capacity, 125 cc. . 4.30 



GAS COLLECTING TUBE, Illinois Steel Company's, of glass without stop-cocks. Capacity, 

 about 250 cc 1.50 



GAS COLLECTING TUBE, Rubber, double acting, for use in filling tubes and bottles with 

 sample to be tested 60 



GAS COLLECTING TUBE, Winkler's, of zinc with two brass stop-cocks. Length, 12 inches; 

 diameter, 4% inches 4.50 



GAS COLLECTING TUBES, United States Bureau of Mines Form, of glass, with two stop- 

 cocks. Capacity, 125 cc. (See Bulletin 97, United States Bureau of Mines, page 53) 6.00 



GAS COLLECTOR, Doremus, for collecting gases from canned goods for analysis. Consists of 

 an adjustable clamp with hollow needle and thumb-screw. A rubber gasket prevents the 

 escape of gas around the needle 4.00 



GAS DENSITY BALANCE, Edwards, developed at the National Bureau of Standards for the 

 rapid and accurate determination of the specific gravity of gas. In point of speed it is far 

 superior to the method of direct weighing of the gas on an analytical balance, and gives an 

 accuracy only obtainable by the latter method when carried out with elaborate precautions. 

 The apparatus consists of a balance beam B carrying a sealed cylinder on one end and a 

 counterweight on the other. The balance beam with its support is mounted in a gas-tight 

 chamber to which is attached a mercury manometer. In operation, the balance case and 

 manometer connections are filled with dry air through the inlet I and the pressure adjusted 

 by removing the excess gas through the needle valve E until the beam just balances, as de- 

 termined by observation through the adjustable lens L of the cross line on the end of the 

 beam. After determining this pressure, the balance is evacuated through E and filled with 

 the gas; the pressure is then adjusted until the beam is again in equilibrium. The specific 

 gravity of the gas is then the ratio of the total pressure (manometer reading plus atmospheric 

 pressure) required to balance the beam in air to the total pressure required to balance it in 

 the gas. Complete as described with manometer and mercury for charging, in carrying case 

 with directions for use. (See Technologic Paper No. 89 of the United States Bureau of 

 Standards) 100.00 



LEVELING BOTTLE for No. 6850, with stop-cocks and reservoir but without rubber tub- 

 ing 9.00 



For PUMPS for use with No. 6850, see general heading Pumps. 



