4*72 Canadian Record of Science. 



Series C will show the effect of increasing the ratio of 

 potassium chloride. There are indications that potassium 

 chloride cannot be completely dried by means of sodium 

 chloride, but these experiments are still in their first stages. 



A single experiment, made for the purpose of bringing 

 to light any causes of variation not taken into account, has 

 proved interesting. Equal quantities of sodium chloride 

 were put into two small tubes and enclosed with water as 

 usual. The invaporation was noted from time to time. Of 

 course, under the same conditions the two quantities of salt, 

 should invaporate at the same rate. As a matter of fact, 

 the two quantities gained water at very nearly the same 

 rate, but, while at first the weight of one tube increased 

 slightly faster, after some time the second tube began to 

 gain weight a little more rapidly than the first. In seeking 

 an explanation of this variation, we noticed that the inside 

 of the first tube was covered with small drops of liquid, 

 while that of the second was dry. This evidently arose 

 from the presence on the former of fine particles of salt 

 exposing a large invaporating surface. Rapid dilution of 

 the salt solution, thus formed, soon destroyed this tempo- 

 rary advantage, and then came into play a second but less 

 marked cause of variation. Tube No. 2 was slightly wider 

 than No. 1, and thus gave a somewhat larger invaporating 

 surface. 



"The Plague of Mice" in Nova Scotia and 

 P. E. Island. 



By the Rev. George Patterson, D.D., New Glasgow, N. S. 



In the early settlement of Nova Scotia and P. B. Island, 

 mention is not infrequently made of mice appearing in 

 such swarms as to become a real plague, entirely des- 

 troying the crops of the new settlers over considerable 

 areas. Diereville, a French writer, in a work published in 

 1699, says: "The Island of St. John (Prince Edward 

 Island) is stated to be visited every seven years by swarms 

 of locusts or field mice alternately — never together. After 



