I860.] Sorbt on Detection of Blood-Stains by Spectrum- Analysis. 209 



also one in the red, having its centre at 1-J above D ; and therefore a 

 trifle lower than Fraunhofer's line C. The intensity of this band 

 shows the amount of change ; and, when it has become complete, the 

 spectrum is very different from that of fresh blood, as shown by No. 4. 

 In this change the bands below D in the green become more and more 

 feint, especially the upper, which finally is only just visible. A larger 

 quantity of blood is required to show spectrum No. 4, than to show 

 No. 2 ; and if the solution be strong enough, only a dirty-brown red 

 light is transmitted, with a dark band in its centre. When kept 

 under similar conditions, the extent of this change serves to show the 

 length of time since the blood was fresh ; and at one time I hoped 

 that by this means it would be possible to determine the time with 

 some confidence, which would often have been very valuable in 

 criminal inquiries. In some cases it might, indeed, be made avail- 

 able, but in and near a town it could not be relied on at all. When 

 sealed up in a glass tube in a perfectly dry state on linen, it would 

 give such a spectrum as No. 3, after having been kept for two or three 

 months ; but when sealed up wet, there is apparently little or no such 

 change. It thus appears that it partly depends on being dry, but 

 will take place independently of being exposed to atmospheric in- 

 fluences. These, however, greatly accelerate it. Exposed to the air 

 on Burbage moor, six miles from Sheffield, and about 1,000 feet 

 higher, one or two miles from any house, the change took place more 

 rapidly, so that the spectrum was nearly as No. 3, after a week or 

 so ; whereas in the centre of the town as much action took place in a 

 few hours. Kept in the house, the rate of change varies very much 

 accordingly as gas is burned in the room or not ; and, when I had 

 ascertained this fact, I concluded that it must be due either to car- 

 bonic or sulphurous acid. I therefore kept some in a flask with car- 

 bonic acid, without being able to perceive any marked effect, whereas 

 sulphurous acid disseminated in a large quantity of air, turned it 

 brown very soon, and caused the spectrum to change from No. 2 to 

 Nos. 3 and 4 ; but, if much acid be present, it produces a more com- 

 plete decomposition, and the absorption-bands are not so distinctly 

 visible. It appears, therefore, that this change in the colouring- 

 matter takes place in dry blood, whether exposed to the air or not, 

 but is greatly accelerated by free exposure to fresh air, and especially 

 by the presence of the sulphurous acid produced by the combustion of 

 coal or gas. Light appears to have little or no influence. Carrying 

 out the nomenclature of Professor Stokes,* I suggest that the brown 

 colouring matter thus produced, should be called " brown cruorine." 

 Though it is apparently dissolved by water, and yields a clear so- 

 lution, yet it is doubtful whether it is soluble in the most strict sense 

 of that term. Close-grained filtering paper removes a great part, and 

 on standing for some time the finer particles collect and subside. It 

 is also difficult to dissolve it from linen, or similar material without 

 repeatedly moistening and squeezing it with forceps, so as to detach 

 the minute particles, some of which remain quite firmly attached ; and 



* 'Proceed. K. S.' xiii. 355, 



