230 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



when the viver-water mixes with the salt waters of the Gulf 

 of Mexico. The cohesion of water diminishes when it holds i 

 saline matter in solution, as was said by Guthrie and was 

 verified by Dr. Hunt. He found that the addition of eight 

 parts of chloride of calcium to 1000 parts of water reduces 

 the size of drops to one ninth, and the j)recipitation of sus- 

 pended clay is made very i*apid when a strong solution of 

 salt is employed. 12 J., X., 277. 



FOEilATION OF FLOOD-MARKS AND GRAVEL BANKS. 



In a communication on the high flood-marks on the banks 

 of the River Tweed, made by D. M. House to the Royal So- 

 ciety of Edinburgh, the author maintains that when the sea 

 stood at higher levels, all the rivers of the country must 

 have likewise flowed in channels of higher levels, and that 

 the flood-marks in question were fornred during that condi- 

 tion of affairs, and not when the rivers were flowing in their 

 existina: channels. With reference to the formation of 

 ridges of drift deposits, the author maintains that they were 

 not due to ice or to river action proper, but that as similar 

 ridges of sand, gravel, or mud are formed now in the sea, so 

 they may have been formed when the districts in question 

 w^ere under the sea. Proceedings Hoy al Society of Edin- 

 hurgh, VIII., 559. 



