388 



KNOWLEDGE. 



October. 1910. 



birth of his daughter Deborah, on " tiie 2nd of 

 May, being Sunday, somewhat before three of the 

 clock in the morning, 1652." Here the ink has 

 faded to a faint brown colour. 



Considerable variations are possible in the pro- 

 portions of iron to gallotannic acid without changing 

 the nature of the resulting black pigment, but if 

 there is a deficienc\- of tannin outside those limits, 

 insufficient pigment will be formed, and the excess 

 of iron will cause the writing t<.) turn brown. .\ lack 

 of tannin to combine with all the iron in the ink is 

 probaliK' the explanation of this faded entrs' in 

 Alilton's Bible. 



The actual pigment formed when ink dries seems 

 to be the same whether the proportion ot tannin to 

 iron be large or small. The writer has made 



this countrx'. the writer has found the total aiuount 

 of solid matter to var\- from l'S9 to 7'94 per cent.; 

 the ash from ()'42 to 2'52 i)er cent. : and the iron 

 from O'lS to rO'J per cent. 



Anah'ses made b\- the writer at intervals of three 

 or four years have shown that the composition of the 

 products of the saiue manufacturer shows but little 

 variation. This is onl\" what was to be expected, 

 since, naturallw w hen a satisfactory article has once 

 been obtained, great care is taken to keep it constant 

 bv using the same proportions of water, galls, 

 d\-estuff and gum. 



In examining writing to ascertain whether it was 

 done w ith a particular ink. it is advisable to prepare 

 a colour scale with that ink, consisting of four 

 washes ranging from the faintest to the darkest 



COLOKATIOXS FIVE MINUTES AETER APPLYING REAGENTS. 



numerous analyses of the deposits produced when 

 solutions of the two substances of var\-ing strength 

 were allowed to stand in contact with the air, and 

 has found them to contain from 5'4 to 0"2 per cent, 

 of iron. 



Of the known insoluble iron tannates the one that 

 best corresponds with this proportion of iron is that 

 described b\- Wittstein [Jalircsh. dcr Clwrn., 1848, 

 28, 221) and by Schiff (Ann. Chein. Pliann., 1875. 

 175, 176) which contains 5'53 per cent, of iron, and 

 has the formula : — 



Fe (C„ H, O,) 3 



Fe (Ci, H,, O,,) 3 



It is probably this compound tliat is produced 

 when ink dries on paper, and that the more nearK' 

 the pro[)ortions of galls and iron-sulphate are 

 calculated to form this tannate without excess of 

 either ingredient, the more permanent will be the 

 writing. 



Many of the commercial inks of the present day 

 deviate widely from this standard, and, as evervone 

 must have noticed, the writing done with some of 

 them will fade considerably, even in the course of a 

 year or two. 



Notwithstanding the probably closelv similar 

 methods of preparation, the composition of different 

 kinds of ink shows wide variations. Thus, out of 

 twent\'-four different varieties of writing ink sold in 



possible tone, and to lea\'e this exposed to the air for 

 at least twent\'-four hours. The scale may then be 

 compared under the microscope with different parts 

 of the writing in (.juestion, and is subsequently used 

 for comparative chemical tests when such are 

 permissible. The broad surfaces of colour are 

 comparable with the surfaces of the written 

 characters as seen under the microscope, and there 

 is thus obtained what practically amounts to a 

 magnified record of the microscopical appearance. 



Lovibond's tintometer will also be found useful in 

 comparing the colours of different specimens of hand- 

 writing, and in matching the colours obtained in 

 chemical reactions with those given by the colour 

 scales prepared from known or suspected inks. 



In some cases microscopical examination on these 

 lines is sufficient to distinguish between the inks in 

 different writings, without the necessity of applying 

 chemical tests. The most striking instance of this 

 kind within the writer's ex[)erience was in the 

 Brinklev poisoning case. The will of an old lady 

 named Blume had been forged by Brinklev, who, on the 

 strength of being her heir, took possession of all the 

 propert\'. Mrs. Blume's relations contested the 

 validity of the will, and Brinkley had, therefore, to 

 prove that it was genuine. One of the witnesses 

 whose signatures were on the will asserted that he had 

 never signed a will at all, but that he had only signed 

 a folded sheet of paper in a public house. As this 

 witness, Parker, stood in the way, Brinkley attempted 



