226 RALPH, ON THE EFFECTS OF 
and, I may add, has proved rather a stimulus to further 
efforts in the same direction. 
A healthy young child fell ill with hooping-cough, and 
after the lapse of a few days was brought to me labouring 
under an early state of pneumonia; extensive puerile re- 
spiration had set in, and there was considerable congestion of 
the cutaneous capillaries of the extremities. A few drops of 
blood were carefully taken from the back of the hand im the 
way I have recommended, 7. e. cleansing the skin first by 
rubbing it with a wet towel, and then puncturmg it and 
taking the blood on a glass slide, without touching the skin. 
The blood presented no unusual appearances, save the presence 
of some dark-coloured bodies larger than blood-dises, to 
which, however, I did not attach any definite importance. 
On the following day more blood was taken, and I noticed in 
two shdes that some bright blue particles were present, 
resembling in colour starch when first acted on by iodine, and 
also some dark purple particles. The following day three 
shdes were charged; these attracted my attention more 
forcibly, and occasioned me considerable perplexity, as more 
blue and purple coloured particles were present, and the blood 
had been carefully taken in every instance; the child, also, 
had been healthy hitherto, and had had no exhibition of iodine 
I knew of, and had not been in other hands than mine. 
4. Prior to the second supply of blood taken, and after the 
first examined, I had ordered Scheele’s prussic acid, and it 
was directed to be continued up to the third time of taking 
the blood. The decided character of these blue particles, 
their persistence for hours on the slide, their increased amount 
in the subsequent examination, all tended to cause consider- 
able perplexity as to their possible origin. After some re- 
flection and one or two chemical examimations, I instituted 
the following experiments, which tend to show that these blue 
particles in the blood are most lhkely composed of Prussian 
blue, and are due to the reaction of prussic acid on the iron in 
the blood. 
5. Ist Exp., Aug. 22nd.—Seven or eight drops of Scheele’s 
prussic acid were given in divided doses to a rabbit; after a 
lapse of five hours, some blood taken from the ear exhibited a 
number of bright blue particles. ‘lwo more drops were given, 
and at the end of twelve hours, two slides of blood showed 
some blue particles; subsequently three drops were given at 
one time (the doses were all more or less diluted with water) ; 
the animal struggled under the influence of the poison, and 
most likely would have succumbed but for the administration 
