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ON MARKING INKS. 
ART. XXIX. —ON THE FORMATION OF FULMINATING 
SILVER IN MARKING INKS. By Mr. Alfred Burgess. 
In the use of marking inks, the inconvenience attendant 
upon the application of the pounce or preparation has always 
been felt to be so great, that those inks which do not require 
such a process, have very reasonably acquired a large measure 
of popular favor ; and if the latter can be proved to possess 
an equal degree of permanence and indelibility, and at the 
same time to be unattended by any other objection, there 
seems to be no reason why the older description should not 
speedily be numbered among the things which have been. 
The question of the comparative indelibility of the two it 
is not my intention to discuss, further than to observe, that 
the term " indelible' 7 is equally inapplicable to both. The 
marks of either can be removed by treating them with am- 
monia and chloride of lime, or with iodide of potassium and 
dilute hydro-chloric acid ; and a method, which, I believe, 
has been till now unknown, and which I discovered while 
conducting experiments connected with the subject of this 
paper, is the application of cyanide of potassium, which re- 
moves the mark as easily as the compound called salt of 
lemons will obliterate that of common writing ink. 
The subject to which I wish particularly to call your atten- 
tion is, the manufacture of marking inks which require no 
preparation, and to the probable existence in some of them of 
a fulminating substance. 
A year or so since, I was about to make for sale a marking 
ink of this description, from a form which I had long had by 
me, the following — 
Take a saturated solution of nitrate of silver, and add there- 
to a saturated solution of carbonate of ammonia until the pre- 
cipitate first formed is re-dissolved. To every ounce of the 
solution so prepared add two drachms of gum arabic and one 
