PHYSICS. r)87 



0-0000550^-). With respect to mixtures, the authors find (1) that the 

 addition of small quantities of alcohol lowers the compressibilitycoefii- 

 cieut of water; (2) that this diminutiou continues to increase until the 

 alcohol constitutes 23 per cent.; (3) that for mixtures containing less 

 than 19 per cent, of alcohol, the coefficient diminishes as the tempera- 

 ture rises from zero upward, there being- for each mixture a tempera- 

 ture where it is a minimum; and (4) that the temi)erature of minimum 

 compressibility is always lower for these mixtures than for water. 

 There appears to be no relation between the temi)erature of maximum 

 density and minimum compressibility of these mixtures. {J. Phys., 

 August, 1885, II, IV, 371.) 



Terquem has translated from Vitruvius an accouut of the process by 

 which Archimedes determined the composition of the crown of Hiero, 

 which differs from that ordinarily received. After the discovery in the 

 bath, he caused to be made two masses equal in weight to that of the 

 crown, the one of gold the other of silver. Then having filled com- 

 pletely with water a vessel of known capacity he plunged into it the 

 mass of silver. A quantity of water equal to the volume of the silver 

 overflowed. Kemoving the metal, he poured water into the vessel until 

 it was again full, measuring the quantity of water thus used. In this 

 manner he ascertained the volume of water corresponding to a known 

 weight of silver. This experiment was then repeated with the mass of 

 gold, the volume of which was found proportionally less. On immers- 

 ing the crown in the same vessel, he observed that a greater volume of 

 water overflowed than was displaced by the mass of gold of the same 

 weight; and from the quantity which overflowed in the former case over 

 that in the latter he calculated the amount of silver which the crown 

 contained. Hence it would appear that Archimedes did not make use 

 of the upward pressure of liquids in this experiment, as is generally as- 

 sumed, but employed a process analogous in principle if not identical 

 with that of the specific gravity bottle. {J. Phys., August, 1885, II, iv, 

 384.) 



Schiff has devised a simple form of ai)paratus for determining the 

 specific density of liquids at high temperatures based on the j^rinciple 

 of the weight thermometer. The bottle used, which has a capacity of 

 8 or lO''' •=•, has a recurved neck over which is a helmet ground air tight. 

 It is filled with the liquid and weighed, then submitted to the required 

 temperature and the excess of liquid allowed to overflow into the helmet. 

 A second weighing after cooling gives the weight of the liquid reuiain- 

 ing and hence of the overflow, from which the density of the liquid at 

 the given temperature is calculated. {Ber. Berl. Chem. Oes., June, 1885, 

 XVIII, 1538; Am. J. ScL, November, 1885, III, xxx, 380.) 



The phenomena of capillarity have received very considerable atten- 

 tion. Worthington has reviewed the method proposed by Quincke for 

 determining surface tensions from the dimensions of flat drops and bub- 

 bles, and has shown that the higher results given by this method over 



