Intelligence and Miscellaneous Articles, 471 



to convey some information to the other, each must be provided with 

 a magnetic needle so strongly touched with the magnet, that it may 

 be able to move the other from Rome to Paris. Now suppose that 

 Johannes and Claudius had each a compass divided into an alphabet 

 according to the number of the letters, and always communicated 

 with each other at six o'clock in the evening ; then (after the needle 

 had turned round 3|- times from the sign which Claudius had given 

 to Johannes) if Claudius wished to say to Johannes, ' Come to me,' 

 he might make his needle stand still, or move till it came to c, then 

 to o, then to m, and so forth. If now the needle of Johannes' com- 

 pass moved at the same time to the same letters, he could easily 

 write down the words of Claudius and understand his meaning. 

 This is a pretty invention ; but I do not believe a magnet of such 

 power could be found in the world." 



Quoted from " the Author " by Schwenter, in his Delicice Physico- 

 Mathematicce, p. 346. 1636. 



ON THE SULPHURIC AND NITRIC COMPOUNDS OF BENZIN AND 

 NAPHTHALIN. BY M. A. LAURENT. 



The author states that the last memoir of M. Piria on sulpho- 

 naphthalidamic acid induces him to publish the labours which he has 

 undertaken on the same subject, but employing different processes. 



He has considered nitrobenzide, anilin, nitronaphthalin, as de- 

 rived by substitution from benzin and naphthalin, and that they 

 ought to possess greater or less analogy with them. 



It is well known that by treating the greater number of them with 

 sulphuric acid, there are obtained sulphobenzidic, sulphanilic, sulpho- 

 naphthalic, and nitrated sulphonaphthalic acids. 



These acids may also be obtained by other processes. Thus, by 

 treating sulphonaphthalic acid by nitric acid, nitrated sulphonaph- 

 thalic acid is formed, SO 3 , C 10 W X. 



If this latter be put into contact with sulphuret of ammonium, sul- 

 phonaphthalidamic acid is obtained, SO 3 , C 10 H 7 Ad. This may also 

 be obtained by means of naphthalidamic carbamide ; it is to be gently 

 heated with concentrated sulphuric acid ; carbonic acid is imme- 

 diately disengaged, and the liquor, diluted with water, deposits sul- 

 phonaphthalidamic acid. Thus : — 



2S0 4 H 2 + C 24 H 16 N 2 0= 2S0 3 C 40 H? N + CO 3 H 2 . 



carbamide. 



By prolonging the action of the nitric acid on the sulphonaph- 

 thalic acid binitrated sulphonaphthalic acid is obtained, the ammo- 

 niacal salt of which, crystallized in fine yellow needles, contains 

 SO 3 C 10 H 6 X 2 + H 3 N. This salt, treated with sulphuretted hydrogen, 

 deposits sulphur, and a new nitrated acid is formed, which appears 

 to be nitrated sulphonaphthalidamic acid, SO 3 C 10 H 6 X Ad. 



Although nitrated naphthalin is unknown, M. Laurent is of opi- 

 nion that this base is formed by treating binitrated naphthalin with 



