Physics and Chemistry. 275 



Gulf of Finland mouth, ^3^ ^"i?^"' '^T'. 



Sound (at Copenhagen), 328 1257) 



Cattegat, at Anholt Isld., 3io 12o9 f 



NorthSea,50milesW. of Jutland, 3i9 12o9 181« 



Ocean, mean, 295 ll9i 181i 



Thus, the animals extract a great part of the solid matter washed 

 lown to the sea by the rain, before it reaches the great ocean, g. h. 



2. Density/ of /ce.— Dufour has determined the density of ice by- 

 ploying a mixture of alcohol and water in 



by the usual methods 

 Every possible care was taken to eliminate 

 the various sources of error which in the best conditions Dufour consid- 

 ered to be equal to 0-002. The ice used was carefully deprived of air 

 h long boiling of the distilled water from which it was frozen. Twenty- 

 two experiments by this method gave a mean density of 0-9175, witb a 

 mean error of ±0-0007, the greatest and least errors being -f0002 and 

 -0-0013. C. Brunner had previously, by another method, fixed the 

 density of ice at 0-91 80. Since the publication of these results ( Cnmptes 

 Hmdus, L, 1039) Dufour has continued his researches by using a mixture 

 of chloroform and rock oil which does not dissolve any portion of the 

 ice, the temperature being kept from — ^° to — 8° C. The results reduced 

 to 0°, with all needful precautions, gave for the mean of sixteen trials 

 0;9178, the greatest and least differences being -f 0-0015 and -00012, 

 tlie mean difference being ±0-0005. This result differs only 0-0003 

 jVoni his former determination and but 0-0002 from that of C. Brunner. 

 The expansion of a volume of water in the moment of freezing is there- 

 ^^fe jh, or J-j- of the volume of the water at 0° C. The former deter- 

 minations of this constant are chiefly, Placidus Heinrich, (1807), 0-905; 

 Thomson, 0-940; Berzelius, 0-916; Dumas, 0-950; Osann, 0-927; 

 Plucker and Geissler, 0-920; C. Brunner, 0-918 ; and Kopp, (1855,) 

 ^■m.~{Comptes Rendus, May 19, 1862.) 

 Chemistry.— 



3. Thallium : a new metal— Ih^ discovery by Crookes of a new ele- 

 inent called thallium, was noticed in vol. xxxii, p. 411. Subsequently 

 *obi8 original announcement of this discovery (May, 1861) Mr. Crookes 

 ^distinguished the true metallic character of this substance, which at first 

 Jas referred by him to the sulphur group. More recently M. La my, a 

 French chemist, without a knowledge of Mr. C.'s prior researches, made 

 tlie discovery of its existence (also by the spectroscope) while examimng the 

 f^Jenium prepared by Mr. F. Kuhlmann from the deposits m the chanibers 

 in which sulphuric acid was made bv the combustion of pyrites. From 

 iW.. .„„:. „ j^^^ succeeded in isolating *^" — "-'«l *h'ch 



^^Jjiusdescrib 



^Tkallium.- 



Thallium has all the character 

 sical properties, greatly resembles 





attention to the preo 

 li, 420, 1852).— Em 



amemoirtothe 

 soon appear in 

 ccupationofthe 



