394 Medico-Legal 



Graham-Smith and Sanger (1903, p. 287) further studied the in- 

 fluence of various materials upon the blood with which they had been in 

 contact. They reported upon their results as follows : 



Experiments upon the detection of blood dried on fabrics. 

 (See Plate and explanation p. 402.) 



"In order to determine to what extent the composition of different 

 cloths influenced blood which had dried on them we procured a 

 number of samples. Human blood was dropped upon these so as to 

 leave some patches unaffected and others saturated. Subsequently the 

 specimens were allowed to dry under natural conditions and were left 

 undisturbed at room temperature and in the light for at least 30 days ; 

 some were not tested for nine months. First a series of control tests 

 were carried out on unstained pieces of cloth in the following way. 

 Small pieces 1x2 cms. were soaked overnight in 2 c.c. of distilled water. 

 In the morning an equal quantity of double normal salt solution was 

 added and the condition and reaction to litmus of the extract recorded. 

 The majority of samples was found to be nearly neutral, some were 

 distinctly alkaline, whilst most of the coarser materials were acid. 

 About "5 c.c. of each extract, if necessary after filtration, were placed in 

 small test-tubes and 1 drop of serum added. No cloudings were noticed 

 except in the markedly acid specimens. After neutralisation with 

 sodium carbonate these also produced no effect on the serum. Certain 

 solutions, especially the acid ones, were found to be opalescent, or slightly 

 cloudy, before the addition of serum, but it was noticed that neutralisa- 

 tion tended to make these clearer. In all our experiments we have 

 avoided shaking the extracts, as we frequently observed deposits and 

 cloudy precipitates at the bottom of the tubes, which in some cases 

 were very difficult to remove by filtration. After removing the 

 supernatant fluid in solutions containing blood the tubes were, however, 

 shaken to ascertain whether sufficient serum was in solution to produce 

 marked foaming. 



In testing for blood, stained patches were treated in the way 

 described above and neutralised if necessary. Two small tubes of 

 each solution were prepared. To one was added one drop of anti-human 

 serum and to the other a drop of anti-ox serum. The results of some of 

 these experiments are given on the opposite page. 



