42T 

 and earthy salts. On analysis this substance gives the formula 



^20 -Hie ^16 ^2» 



corresponding to 



C20 H,o O4 + S.j Og + He Oq. 



That the sulphuric acid exists in this body, as such, is 

 shown by the fact that, on treating it with pure potash, the 

 whole of the sulphur separates as sulphate of potash. This sub- 

 stance is denominated sulpho-sassafras by Sir Robert Kane. 



During the reaction of the sulphuric acid and oil of sassa- 

 fras, in order to produce this body, very small quantities should 

 be operated on, and the mixture kept perfectly cool, so that 

 no effervescence, or violent reaction, should take place. If 

 there be the slightest elevation of temperature, the substance 

 in question is decomposed, sulphurous acid is evolved, and a 

 resinoid black material is produced, which does not contain 

 sulphuric acid, but for which, from the complexity of the re- 

 action accompanying its formation, and the great difficulty of 

 obtaining it absolutely pure, Sir Robert Kane does not at pre- 

 sent wish to propose a formula. 



M. Donovan, Esq., continued the reading of his paper on 

 the Nature of the Agency which produces the Effects called 

 Galvanic, Electro-magnetic, Magneto-electric, and Thermo- 

 electric. 



To support the opinion of identity, and to effect other ob- 

 jects, one of the chief of which is to show the absolute quan- 

 tity of electricity with which matter is associated, Professor 

 Faraday makes use of the following law, viz. : " If the same 

 absolute quantity of electricity pass through the galvanometer, 

 whatever may be its intensity, the deflecting force upon the 

 magnetic needle is the same." The general method of proof 

 of the truth of this law was to charge a Leyden battery with a 

 certain number of turns of a powerful plate electric machine, 

 varying the number of jars employed from eight to fifteen ; to 

 transmit the charge through a galvanometer, and to note the 



