136 
a caoutchouc) is seeded with caoutchouc particles or treated with 
other appropriate ferment at 6o c C. in an atmosphere of nitrogen. 
Later a method was patented of preparing the '‘ferment.” To 
obtain this the “ thick deposit ” from a caoutchouc solution in 
benzine, kept at a temperature of 50X. and exposed to daylight in a 
closed bottle, is re-dissolved and then precipitated again by alcohol. 
The precipitate is scattered over the surface of a mixture of coal tar 
and boric acid which is maintained at 50C. in an atmosphere of 
oxygen. A brownish-grey powder is stated to be formed on the 
walls, and this is the “ ferment ” in an active form. Prior to the 
last process, Jasset (1902) stated in his specification that coal tar 
{4 parts) and boric acid (I part), heated until the burning vapours 
were coloured green and then kept at 6o°C. in a current of oxygen, 
yielded a brown highly elastic body to suitable solvents after drying 
on a water-bath. Phosphoric or iodic acid may replace boric acid. 
An American patent, by Dupont and Franklin (1903) gives a variation 
of the above, since the tar and boric acid are dissolved in alcohol, 
heated until vapours burning with green flame are evolved, then 
oxygen is passed through the mixture. Blum and Carpenter (French 
patent, 1909) propose to obtain a glutinous mass consisting of a 
hydrocarbon of the formula ( C 5 Hs ^ by subjecting vegetable 
substances, such as peat, to fermentation at about 60 C., and simul- 
taneously or subsequently to a reducing process. The enzyme is 
stated to be present in imperfectly- formed caoutchouc, or an “enzyme 
which will produce alcohols of a series higher than the ole fine series ” 
may be used. The reducing agent is a nitrogenous compound, pre- 
ferably the red substance resembling seed in red Upper Congo rubber, 
with the addition of mineral salts. In 1908 the same two patentees 
specified a process to produce “ synthetic Para rubber” by treating 
with a nitrogenous derivature of irone, the mucilaginous mass “con- 
taining a large percentage of isoprene ” produced from fermented 
peat, etc. The irone was stated in a subsequent patent to be obtained 
from roots of species of Iris; The irone is converted by chlorine into 
a hydrochloride, then by addition of a suitable substance, preferably 
an amide, into a nitrogenous compound. Protein-coagulating enzymes 
are known to occur in the latex of rubber-producing plants, but 
exactly in what form caoutchouc pre-exists is not known ; but to 
produce artificial rubber from tar by a volatile enzyme capable of 
growth does not accord with known facts. 
Rubber substitutes have met with greater success since at present 
considerable difficulty is experienced in obtaining rubber goods free 
from substitutes. Their use as a cheapener is responsible for many 
of the defects to which rubber articles are liable. The non-resistance 
of rubber substitutes to the action of potassium hydrate is the method 
used for the detection and estimation of substitutes. Among the 
multifarious substances proposed to be employed for the diluting 
rubber the oxidation-products of drying-oils are the basis of the main 
modern class. Dry oxidation of a suitable fixed oil, usually linseed 
oil, is affected with a manganese dioxide, etc., or in the wet process 
