^i On li'ie Composition of JFrillng tnk. 



Iience a compound of alumina not very dissimilar to afum. 

 And lopaz, who.-e sinsular ingftdieuts, discovered by Mr. 

 Klaproil), have called forili a query from the celcbraled 

 Mr. Vaii(]iielin, with regard to the mode oi' their exisience 

 togcllier*, will ba likewise a comprnd salt, consisiing ot" 

 silicate of alinnina and fluate of al(.m)lna. 



Our acquaintance wiih the composition of the several 

 mineral substances is yet far too inaccurate lo render it 

 possible to poini out wiih any degree of certainty the one 

 of which zeolite is an hydrate; however, the agreement of 

 the two substances in the nature of tlicir constituent part?, 

 and in their being both electrical by hear, diiecis conjecture 

 towards lourmahne. 

 tit. J.imti'5 Place, Jiii. 22, ISl 1. 



jIddiLion to ike Account of native Minium. 



After I had communicated to the president the accouiYt 

 of the discovery of native minium, printed in the Philoso- 

 phical Transactions for IbOO, I learned that this ore came 

 i'roiij the lead mines of Bre) lau in Westphalia. 



Vr. Report made to the Institute on a Memoir, by M. Tarry, 

 on the Composition of JVriting Ink. By Messrs. Beii- 



TIIOLLKT, VAVaUELlS,cnd DEVKUXf. 



FkiK object proposed by M. Tarry in his memoir is to ex- 

 plain : 



1. The processes employed for Jischargmg wntmg fiom 



paper. 



2. The processes for rcviWog writings which have beca 

 apparently obliterated. 



3. The best way to improve common ink. 



4. Finally, the 'discovery of an iuk which should resist 

 all chemical agents. 



We shall no.v give an abridgement of these four articles; 



ARTICLE I. 



Processesfor discharging Writing. — ^The art of discharging: 

 writing is very ancient, and the means employed are very 

 simple. In fact> we know that it is sufficient to moisten a 

 written paper with any acid, when the writing will gradually* 

 disappear. But all the acids cannot be eniployed with equal 

 success. ,Somc leave a stain on the paper which is not 



* /I'lnaics 4'i Museum d'lJiil. Nut. tome vi. p. 2i. 

 t AniiiiUi lie Chiiuie, turtle Ixiv. •). 19i. 



easily 



