420 PROFESSOR TRAILL ON THE COMPOSITION OF A NEW WRITING-INK. 



the subject of a prize offered by the National Institute of France, which has not yet, 

 I believe, been awai'ded to any competitor. 



The important interests involved lent an additional interest to the investiga- 

 tion, and engaged me in a long series of experiments, the results of which I beg 

 leave now to submit to the Royal Society of Edinburgh, as a body weU fitted to 

 decide on the merits of my proposition ; and, should the discovery be deemed 

 worthy of that distinction, to communicate it to the public. 



Before proceeding to the more immediate subject of this paper, it may not 

 be uninteresting to review the general results of my experimental investigations 

 on various substances, before I succeeded in forming a good durable writing-ink ; 

 and a knowledge of my previous failures may at least save the time of future in- 

 vestigators. 



The substances which either whoUy or nearly efface common writing-ink are 

 chiefly, 



1 . Solutions of clilorine | 



2. Cliloride of lime with a weak acid | 



3. Clilotidc of antimony C entirely. 



4. Dilute nitro-muriatic acid I 



5. Oxalic acid / 



6. Diluted nitric acid f 



7. ■ . . sulphuric acid j in a great measure. 



8. ... hydrochloric acid 



9. Solutions of potassa \ 



10. ... of soda \ greatly impair its colour. 



11. ... of ammonia I 



These substances, with the exception of pure soda, which acts just as potassa. 

 were tried on different inks ; and resistance to then- effects, either when applied 

 singly or in succession, was considered as the criterion of the durability of the 

 ink. 



Series I. Experiments with prepared Paper. 



It was imagined that, by first impregnating unsized paper with substances 

 capable of affording deep colom'ed precipitates from metallic solutions, and then 

 sizing the paper, that the precipitate from a metallic ink might be so fixed in 

 the paper as to resist these chemical agents. 



Unsized paper was therefore soaked in the following solutions : 



A Infusion and tincture of galls. 



B Prussian alkali, or fcrro-cyanide of potassium. 



C Common salt, or chloride of sodium. 



D Phosphate of soda. 



E Hydriodate of potassa, or iodide of potassium. 



F Bichromate of potassa. 



