Tests icith Precipitins 401 



solution and gradually deepened, being considerably denser in No. IX 

 than in No. I. 



After the passage of CO2 and filtration every solution was clear, with 

 the exception of V and VIII, and produced no deposit on standing. 

 The two mentioned were opalescent. No clouding occurred on the 

 addition of anti-human serum. 



Two sets of quantitative experiments were carried out with these 

 soils. In the first 1 c.c. of finely divided soil was placed in a test-tube 

 Avith 1 c.c. of human pleuritic exudate and 5 c.c. of water. After 4 days 

 5 c.c. of double normal salt solution were added to each, making a dilution 

 of 1 in 11 of pleuritic exudate. In the second series 1 c.c. of dry earth 

 was allowed to act for 4 days on 1 c.c. of pleuritic exudate. At the 

 end of this period the specimens were diluted to 1 in 11 with salt 

 solution. 



These solutions were treated with CO2 as described, and the 

 precipita measured quantitatively. 



The above table shows that the quantity of precipitum obtained did 

 not decrease in proportion to the increase of the lime, which was 

 apparently never present in sufficient quantity to materially aff'ect the 

 reaction. Excess of potash probably accounts for the low figures 

 obtained in No. V, and possibly No. VIII (p. 83). In neither of these 

 could a clear solution be obtained. Whatever may be the cause of the 

 variations in the quantity of precipitum obtained, these experiments go 

 to show that blood mixed with ordinary earth can be readily detected 

 if present in sufficient quantity and that its specific character remains 

 unaltered. 



From our experiments on earth and lime salts we have drawn the 

 following conclusions: (1) that the intimate mixture of lime with blood 

 completely destroys the latter; (2) that a clouding occurs in the 

 N. 26 



