On the Composition of Writing Ink, $7 
lastly, there are some which are first pale and then he 
come very black. 
All these differences arise from the nature of the sub- 
stances which have been employed in the making of the 
ink. 
Convinced of the advantage of having a good article 
of this kind, the author commenced a series of expe- 
riments, but is forced to admit that he has not discover- 
ed any receipt superior to that which has been publish- 
ed by Lewis. This ink, according to our author, com- 
bines every advantage : but we must observe that it is no 
more exempt than the rest from being dissolved in the 
acids, and in this respect it has an inconvenience which 
those who wish to discharge writing from paper know 
very well how to profit by. This circumstance, no doubt, 
induced M. Tarry to make some new experiments in 
order to obtain an ink which should be inalterable by 
chemical agents : and he appears to us to have succeeded 
in his object 
ARTICLE IVe 
Discovery of an Ink which resists the Action of Chemical 
Agents . 
The author describes his invention in the following 
words : 
“My ink is founded upon principles different from those 
of all others. It contains neither gall nuts, Brazil wood, 
or Cam peachy*, gum, nor any preparation of iron: it is 
purely vegetable, resists the action of the inbst powerful 
vegetables, the most highly concentrated alkaline solu- 
tions, and, finally, all the solvents. 
“ The nitric acid acts very feebly upon the writing per- 
formed with this ink. The oxymuriatic acid makes it 
assume the colour of pigeo*n ? s dung. After the action of 
