432 Messrs, J. G. M'Kendrick and J. Dewar on [June 18, 



From these results it is evident that the ice under examination was 

 very far from being an homogeneous body; and, indeed, nothing else 

 could be expected, when it is borne in mind that the ice in question 

 owes its existence, not only to the bond fide freezing of sea-water, but 

 also to the snow which falls on its surface and is congealed into a 

 compact mass by the salt-water spray freezing amongst it. 



The ice formed by freezing sea-water in a bucket was found to have 

 formed all round the bottom and sides of the bucket, and forming a 

 pellicle on the surface, from which and from the sides and bottom the ice 

 had formed in hexagonal planes, projecting edgewise into the water. 

 The water was poured off, the crystals collected, washed with distilled 

 water, pressed between filtering-paper, and one portion melted. It 

 measured 9 cub. centims., and required 4 cub. centims. silver solution, 

 corresponding to O0142 gramme chlorine, or 1*5780 gramme per litre. 

 The other portion was used for determining the melting-point. The 

 thermometer used was one of Greissler's normal ones, divided into tenths 

 of a degree Centigrade, whose zero had been verified the day before in 

 melting snow. The melting-point of the ice-crystals was found to be 

 1*3. The temperature of the melting mass was observed to remain 

 constant for twenty minutes, after which no further observations were 

 made. 



In the same way the melting-point of the pack-ice was determined. 

 The fresh ice began to melt at 1 ; after twenty minutes the ther- 

 mometer had risen to 0> 9, and two hours and a half afterwards it 

 stood at 0'3, having remained constant for about an hour at 0'4. 

 Another portion of the ice rose more rapidly ; and when three fourths of 

 the ice was melted, the thermometer stood at 0. 



These determinations of the temperature of melting sea-water ice 

 show that the salt is not contained in it only in the form of mechanically 

 enclosed brine, but exists in the solid form, either as a single crystalline 

 substance or as a mixture of ice- and salt-crystals. Common salt, when 

 separating from solutions at temperatures below 0, crystallizes in 

 hexagonal planes ; sea-water ice, therefore, may possibly have some 

 analogy to the isomorphous mixtures occurring amongst minerals. 



XV. " On the Physiological Action of the Chinoline and Pyridine 

 Bases." By JOHN G. M'KENDRICK and JAMES DEWAR, 

 Edinburgh. Communicated by Professor J. BURDON SAN- 

 DERSON, M.D.,, F.R.S. Received June 11, 1874. 



(Abstract.) 



It is well known that quinine, cinchonine, or strychnine yield, when 

 distilled with caustic potash, two homologous series of bases, named the 

 pyridine aad chinoline series. Bases isomeric with these may also be 



