180 
gave results imeem parallel with those mentioned above. This 
latex is interesting, as it is readily clotted by churning. A soft 
spongy clot is forried in a few minutes containing in its meshes 
the greater part of the solution in which the rubber-particles were 
suspended. If this clot is cut into alive while still soft and 
pressed between sugar-cane crushers, or in a heavy press, the 
bulk of the solution is extracted er a fairly pure rubber is 
fou On drying, it does not ve off the putrid smell 
characteristic of the ordinary Ceará be 
Other latices can also be clotted by churning, but the process is 
a long one, 
he latex of Hancornia x wem and of Mimusops globosa gave 
similar rakit on centrifugalizing. In the case of the latter, the 
pink colouring-matter hich characterizes ‘ balata’ was found to 
have separated as a thin layer at the bottom of the tubes 
Artocarpus incisa contains a very viscous latex employed by 
the Brazilians as a bird-lime or as a substitute for glue When 
diluted and centrifugalized it separates ed giving a creamy 
white layer which dries to a resinous mass somewhat resembling 
gutta-percha. At the ordinary temperature this is quite hard and 
iu but if the temperature is raised sli ghtly it becomes plastie, 
at the temperature of boiling water it is soft and excessively 
isk. The substance is soluble in carbon bi-sulphide, and 
nsoluble in Aloch k nd water 
Urostigma Gamelleira* yieldsa similar sühebition of a chocolate- 
brown colour 
We thus see that cue mere action of centrifugal force effects the 
separation of rubber; and from the failure of the processes 
usually employed, involving the use of chemical reagents, to 
bring about the clotting of the separated and washed rubber- 
les, we must infer that no chemical change occurs in the 
rubber itself, and that the cause of coagulation iun be looked for 
in the medium in which they are suspended. 
From our knowledge of the constitution of latex, it is evident 
that the proteids are the most likely substances to cause this 
icem treated with acids, alkalies, excess of salt, &c., and when 
oiled. 
Unfortunately few latices have as yet been examined for their 
proteid constituents, chiefly on account of the diffieulty of 
obtaining them in their natural condition in European laboratories, 
owing to their coagulating and undergoing decomposition during 
the journey from the tropics.t The ag tone so far made 
prove t the presence of albumin, globulin, albumose, and peptone 
in several prise Resin) latices. t In the clear solution left after 
NT IE of the rubber-particles the xantboproteie reaction 
always showed the presence of proteid matters, but under the 
circumstances it Bed impossible to identify them. 
Now albumins are characterized by the coagulation of their 
solutions on heat ing, especially in the presence of dilute acids, 
and globulins or their ready precipitation with the salt-solution 
and their coagulation on heating. 
* Mart. Fl. Bras. 4. i. 93, Ficus doliarum of Mart. Sys. Mat. Med. Bras 8. 
t This does not apply to the latex of Mimusops globosa, or Hancornia iun, 
both of which may be kept for months w Im undergoing any change. 
I J.R Green, Proc, Roy. Soc., 1886, 
