V. HYDROMETEltS. 147 



674. Alcoholometer, consisting of two cylinders of ebonite 

 and brass, keyed together. G. Recknagel, Kaiser si autern. 



The alcoholometer is not liable to break, and answers all requirements of 

 accuracy in reading. 



675. Areometer of ebonite and brass, with adjustable cylinder. 



G. Recknagel, Kaiser si autern. 



This not being liable to be broken can be used for educational purposes as 

 well as for practical application. 



The upper terminal level plate is adapted for placing small weights on it, 

 by means of which the meaning of the dividing lines can be demonstrated. 

 The instrument, moreover, is arranged with a cylindrical slide, which can be 

 extended to the double volume of the divided spindle. If the scale is ex- 

 hausted, the slide is to be pulled out a volume more, and the scale is then again 

 at disposal for use. 



The most suitable for instruction and practice is the uniform scale of the 

 Gay Lussac areometer. As, however, there is easily room for four scales, the 

 others can be arranged for direct indication of specific weights, or, like the 

 present models, for alcoholometry. 



676. Areometer Case, containing three standard areometer- 

 cylinders, for determining the specific gravity of all kinds of 

 liquids, with indicator scale fused to them. W. Zorn, Berlin. 



677. Areometer. The indicator scale is not fused into the 

 glass, but fastened only with sealing-wax. W. Zorn, Berlin. 



Each of these areometer-cases contains three glass spindles, which, loaded 

 at the top in a similar manner to Nicholson's metal spindles, with weights, 

 indicate with the greatest accuracy the specific weight of all liquids. 



The liquid to be tested must be brought to a temperature of 15 Celsius ; if 

 one of the spindles is inserted in the liquid, so many weights must be placed 

 on the glass plate as are required to make the spindle sink as far as the black 

 mark on the milk-white glass line in the neck of the spindle. 



The lightest spindle embraces all liquids from 0-650 to 1,000; if this 

 has been used, 650 must be added to the weight placed on the spindle. If 

 the medium (1,000) spindle has been employed, 1,000 must be added to the 

 weight, and at the heaviest (1,400) spindle, 1,400 must be added to the weight 

 placed on the same. The sum' obtained will give the specific weight of. the 

 liquids with an accuracy extending a little over the third decimal. 



The proof of the correctness is simple ; it is only necessary to have a good 

 pair of scales and some distilled water : 



650 weight = spindle 0*650 ; spindle 0-650 + 

 350 weight = spindle 1,000; spindle 1,000 + 

 400 weight = spindle 1,400. 



The construction of these areometers is new. i'or many years the exhibitor 

 had constructed similar areometers, consisting, however, of two spindles only, 

 which were very much liked, under the name of Wittstock's areometer, on 

 account of their accuracy ; but it was too fragile, owing to the light spindle 

 (because there being but two of them) having to carry too much weight. 

 Moreover, the late Privy Councillor, Dr. Wittstock (apothecary to the Royal 

 Court at Berlin), had devised a peculiar proportionate weight to the same, 

 from which the spindles had derived their name, but which is now no longer 

 in use. 



K 2 



