OF MICROSCOPIC OBJECTS. 193 
For the injecting fluid, take 24 ounces of the coloured 
liquid thus prepared, and three ounces of good gelatine. 
Allow these to remain together twelve hours, and then 
dissolve by the heat of a water-bath; after which it should 
be strained through fine muslin. 
As this injecting fluid contains gelatine, the hot water, 
and other contrivances mentioned in a former part of the 
chapter, will be necessary here also, but no peculiar treat- 
ment will be required. 
Since writing the above concerning carmine injection, I 
have had the misfortune to lose my friend Mr. Dale, but not 
before we made scores of experiments together, with this 
formula. Our experience, 1 may say without vanity, justi- 
fies me in declaring that a good operator can get results 
equal to any that he will receive from the Continent, as far as 
colour and distinctness are concerned. The colour, being 
thoroughly precipitated, cannot stain the tissues, and the 
course is thus clear and well defined. If the object is small, 
it is well to use the mixture with 25 or 30 ounces of water 
instead of 40; but, with this exception, I know of nothing 
that needs alteration. I have, time after time, measured 
vessels thoroughly filled with good colour — especially 
amongst fatty portions,—and found them betwixt 1-3000th 
and 1-4000th of aninch. As some young students might 
say “ Give me an account of something done with it,” I will 
endeavour to describe my use of part of a horse’s leg. My 
friend Mr. Hepworth wrote to me that he had a horse’s leg, 
and should be glad if I would come over with sufficient car- 
mine to inject it. I took three pints of solution, and may 
here mention that, with a very slight loss indeed, all this 
liquid was thrown into ovr subject. The leg was cut off 
just beneath the knee, and before using it we allowed it to 
remain in water about 80° or 90° Fahrenheit two or three 
hours, and then introduced our syringe into an artery at 
the top. As I have no faith in any mechanical contrivance, 
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