70 Sheppard, on Colour in Organised Substances. 
I am by no means sure that it is harmless — it certainly pro- 
duces headache and sickness ; to such an extent is this the 
case that experiments with the substance cannot be carried on 
in the house. I may ask, and not without reason, has the 
change the organisms produce in organic fluids, in their con- 
sistency as well as their colour, any relation to the alteration 
of the physical qualities of the blood in typhus ? Here is a 
ferment which in a few hours is capable of producing a total 
disorganisation of the fluid to which it is added, and the film 
is composed of materials which abound in the foul undrained 
localities whence fever is never absent, and in the impure 
water of town wells. I hope before long to be able to give 
you more information ad hoc. 
The solution of coloured albumen obeys all the chemical 
laws to which albumen itself is obedient, but it becomes much 
less tenaceous — ropy after it has acquired the colour. 
Reaction of the film upon various organic substances. 
Darkness assists the changes, and is almost necessary for 
the production of them. 
Soluble albumen . — Albumen at the bottom of a glass, film 
dropped on it, and water above, action commences instantly, 
and colour of any intensity can be obtained. 
Coagulated albumen. — No action; partially coagulated; 
action in inverse proportion to the completeness of the coagu- 
lation. 
Starch . — Action slow, but continuous ; colour has a pre- 
ponderance of blue. 
Gluten . — Action rapid at first, then production of colour 
soon ceases, but fermentation with copious evolution of gas 
continues. 
Gelatine . — Patent gelatine swollen and softened by cold 
water — no action in twenty-four hours. 
Cooked beef fat . — Action tardy, but a good colour ; appears 
at last showing the different tints in different aspects very 
well. 
Coloured fluid poured upon soluble albumen . — The coloured 
liquid has not yet propagated the fermentation (for want of a 
better name) when added to fresh albumen where care has 
been taken to exclude all pieces of the film. The film 
coagulates albumen in a* partial manner ; when dropped into 
diluted white of egg it produces threads of very opaque, very 
* Not meaning incompletely, but as if selecting some parts for coagula- 
tion and avoiding them. 
