392 Medico-Legal 



so as to point out the possibility of a mistake occurring under such 

 circumstances. 



It appears that the effect of oil on blood is to lessen the reaction. 

 This is probably due to the blood being coated with a film of oil, and 

 therefore not so easily passing into solution. 



B. Blood dried on organic 'materials. 



The experiments quoted below have been inserted here to show the 

 effects of age on blood dried on organic fabrics, but further experiments 

 (p. 394) indicate some of the fallacies which may arise from the 

 character of the materials. It happened, however, that in the specimens 

 chosen few were of such a character as to give rise to possibilities of 

 error. 



The blood-stained materials tabulated below were all obtained from 

 Scotland Yard, and with them two series of tests were conducted, the 

 antiserum employed in the second being more powerful than that in 

 the first. 



In the first series very small quantities were employed, but in the 

 second the amount in each case was slightly greater. It was, however, 

 not found possible on either occasion to obtain more than very small 

 fragments, and, moreover, none of the specimens, with the exception of 

 No. 11, were markedly encrusted with blood. The one exception, a 

 specimen of hair, 28 years old, was in some parts thickly plastered, and 

 gave well-marked reactions with each antiserum. 



The following table shows that numbers 1, 2, 3, 4, 6, 8, and 11, or 

 64 /o f the whole, gave well-marked reactions, their ages varying from 

 3 to 28 years. In No. 5 the paper was badly burnt and the capacity for 

 reacting was probably destroyed by the heat. Nos. 7 and 10 produced 

 alkaline solutions, and in each case the reaction with anti-human serum 

 was very slight. This was probably due to the retarding influence of 

 the alkali, which has been discussed on p. 79 et seq. At the time these 

 experiments were carried out we were not aware of this action of alkalis. 

 The negative result of No. 9 may have been due to its acidity. No. 12 

 failed to react, but we were unable to discover any reason for this. 

 The controls in all cases were negative. 



As so little material was available the results may be looked upon 

 as most satisfactory, for it can scarcely be doubted that more distinct 

 reactions would have been obtained had it been possible to make more 

 extensive use of the specimens." 



