1841.] Examination of some decayed Oriental Works. 577 



'^Iron . (Tinct Galls. 



I ^*^"' " (Prussiate Potass. 



Absence of «j ^^^^^^^ Ammonia. 



(^Nitric acid, Mur. Acid and Gold leaf. 



4. The solution being evaporated, a portion of the carbonaceous 

 matter became insoluble. Cold alcohol did not act on the gummy mass 

 left, nor was any soluble salt obtained by it. 



5. Acetate of barytes was added to the clear solution, and the pre- 

 cipitate dried at a low red heat, weighed 2.25 grs. which would give 

 0.75 grs. of sulphuric acid for each half, leaf or 450 grs. (by weight) 

 for a volume of 300 pages. This is of course but an approximative 

 calculation ; but we may be fully satisfied by it^ that the quantity of free 

 sulphuric acid in the book, is quite sufficient to produce the mischief. 



6. This decomposition of paper, so as to crumble to pieces between 

 the fingers, (though without being much discoloured,) is familiar to every 

 chemist, as happening daily to the edges of his filters with acid and 

 alkaline solutions of but moderate strength. The discolouration may 

 arise from the ink and iron carried by capillary attraction through the 

 fibres of the paper with the acid, or finally, since the ink remains 

 unaltered in most parts, from the carbonisation of the paper. 



7. I suppose the excess of acid to have arisen from the use of an 



excess of crude sulphate of iron {heerakosh) in the ink, which, either 



ignorantly or by design,* is added in too large quantities, and thus an 



extra portion of sulphate of iron, in addition to the sulphuric acid set 



free in the composition of ordinary inks, remains in it. Sulphate of 



iron is a sulphate of the protoxide of iron, and the vegetable matter 



of the paper being particularly prone to combine with both the acid 



and the iron, of which last the common iron-mould spots are such 



familiar examples ; it may easily be supposed, that in our humid climate, 



with its high temperature, new chemical combinations must soon take 



place amongst the varied principles of paper and ink-starch : gum, 



vegetable fibre, gallic and sulphuric acids, iron, lime, and potass ; of 



which, as we see, the result is, that the carbonaceous matter of the paper 



alone remains. An analogous effect is observed by mineralogists upon 



labels or wrapping papers, when, by the decomposition of pyrites, sul- 



* By design. There are secrets in all trades, and our Moulvee informs me, that the 

 copyists of '' Arabisthan" well know that their books will not last too long, and so spoil 

 trade. 



