222 Miscellaneous Intelligence 



several seconds, as drops of water or alcohol, and other substances, 

 do upon masses of their own fluids. During this time they retain a 

 high temperature, cooling- by comparison very slowly ; but on a 

 sudden, when at a certain point, they come m contact with the water, 

 hiss, are quenched, forming steam, and instantly sink. When these 

 globules have been afterwards examined, they have been found now 

 and then hollow, but generally solid, highly polished, very round 

 and heavy, as slags ordinarily are. — M. F. 



4. On the Tension of the Poles of a Voltaic Battery when com- 

 municated or independent. — The well-known effect of an accumu- 

 lation of electricity at the poles of the Voltaic battery, when not in 

 connection with each other, has been experimented upon by M. 

 Marianini. He finds that, when connected, the diminution of ten- 

 sion is at first rapid, and then more slowly reaches the limit which 

 is consistent with the nature and extent of the conducting substance. 

 Thus, with a new Voltaic apparatus, having its poles connected 

 with an electrometer, the tension, before they were communicated, 

 was 12°; being communicated, it became 9°.5in 5'^; 8°.5 in IC; 8° 

 in 30''; 7° after 1'; 6° after 2^ 5° after 5'; 4° after 10^ and rather 

 less than 4° after 15, 20, 30, 40, and 60 minutes; but differences 

 were produced according to the nature of the fluid used as a con- 

 ducting medium. 



On breaking the communication after 5 minutes, when the ten- 

 sion was 5°, the latter rose to 7°.5 ; in the space of 30'' to 8°.5 ;. 

 after a minute, to 10°. 5 after 3'; and to 12°, or the original tension, 

 after 5J minutes. 



Ajn electro-voltaic apparatus, which had lost its tension in con- 

 sequence of communication between its poles, had it very rapidly 

 restored when it was connected with a second apparatus turned in 

 the contrary direction, so that the poles of the same kind were con- 

 nected together ; and when this combined action was prolonged, 

 the first apparatus withdrawn from the circuit gave evidence of a 

 tension superior to that which it originally possessed. This 

 increased power was observed by the condenser, and also by the 

 magnetic needle, the deviation of the latter l)eing sometimes thrice 

 as great as without this peculiar eflect. M. Marianini thinks that 

 this result may lead to important improvements of the pile. — BiiU^ 

 Univ. A. viii. p. 317. 



5. Oil Efflorescence, by M. Gay Lussac. — Many salts when 

 exposed to air effloresce, i. e. lose their water of crystallization and 

 fall into powder; it is generally supposed that these salts, when 

 tlius effloresced, are anhydrous. Having known for a long time 

 that this was not the case, I have made some experiments on the 

 salts which are principally efflorescent. 



Hydrated sulphate of soda exposed to air, even in damp weather, 

 loses all its water of crystallization. 



Phosphate of soda soon becomes opaque, but does not change its 



