924 APPENDIX. 



Calorimeter ; Regnault's apparatus for specific heat of gas ; 

 Jamin's Calorimeter; Bensen's Absorptiometer ; Regnault's Air 

 Thermometer ; Regnault's apparatus for specific heat of liquids ; 

 Regnault's apparatus for determining the tension of steam at high 

 pressure ; Regnault's apparatus for determining the tension of 

 vapour from to 100; apparatus for compression of liquids by 

 Regnault's Piezometer ; Doyere's gas analysis apparatus ; Doyere's 

 Pipette for gas analysis apparatus ; Favre's Mercury Calorimeter ; 

 Regnault's apparatus for estimating the specific gravity of solid 

 bodies. 



63O. Air Pump, by Spencer, of Dublin. Prof. W. F. Barret. 



This air pump has no valves between the barrels and the receiver, hence 

 it is free from regurgitations of air, and is capable of making a vacuum nearly 

 equal to that obtained by means of Sprengel's air pump. The ends of the 

 pistons and barrels are conical, and, when they are in contact, no cavities 

 remain. All the air in the barrels is therefore expelled at each stroke of the 

 piston ; the effect is the same when it is highly rarefied. The horizontal 

 portions of the pump admit of the barrel being brought into close connexion 

 with the plate, and leaves the valves accessible for cleaning or repairs. 



679. Alcohol-meter. 



Siemens Brothers and Co., Charlottenburg. 



An apparatus for measuring simultaneously the quantity of spirit flowing 

 through it, and the per-centage of absolute alcohol contained in that spirit. 

 The quantity is measured by a revolving drum imparting motion to a counter 

 under the control of a hydrometer containing pure alcohol, which registers 

 the per-centage. The measurement is unaffected either by the velocity at 

 which the spirit enters or by the friction of the bearings of the spindles of the 

 drum. 



680a. Improved Portable Spireometer. E. Cetti 8? Co. 



69 7 a. Stand and Burner for Sensitive Flames. 



Professor W. F. Barrett. 



The sensitive flame is an illustration of resonance. The vibrations accepted 

 by the flame are those which the flame itself would emit when roaring. A 

 flame to be sensitive must be brought to the verge of roaring by a proper 

 adjustment of pressure on the gas supply. The flame is then in unstable 

 equilibrium, and a feeble sympathetic vibration will then produce the same 

 effect on the flame as a slight increase in the gas pressure. 



The flame to be extremely sensitive must be fed with gas which flows 

 smoothly and freely to the orifice. A bell gas holder is far better than a gas 

 bag for obtaining the necessary pressure. The gas trays must be open and 

 pressure adjusted by altering the weights on the gasholder. The stand 

 shown allows the gas to flow smoothly, and the best burner is a steatite "jet 

 photometer " burner carefully enlarged till it gives the tallest possible flame 

 under a pressure just short of roaring. Such a flame with good gas can be 

 had 2 feet high, shrinking down under the influence of a sound to less than 

 one half this height. With similar burner and pressure the quantity of the 

 gas is accurately determined by the degree of sensitiveness of the flame. 



