feature of the invention, the model will be constructed of that
material.

32--The model must not be more than one foot in length, width or height,
unless the Commissioner of Patents shall admit working models of
complicated machines of larger dimensions.

33--Models belonging to patented cases will not be taken from the office
except in the custody of a sworn employee especially authorized by the
Commissioner of Patents.

SPECIMENS.

34--When the invention or discovery is of a composition of matter the
applicant shall furnish a specimen of the composition and of its
ingredients sufficient in quantity for the purpose of experiment.

35--In all cases where the article is not perishable a specimen of the
composition claimed, put up in proper form to be preserved in the office
must be furnished.

INTERFERENCES.

36--An interference is a proceeding instituted for the purpose of
determining the question of priority of invention between two or more
parties claiming substantially the same patentable invention or
discovery.

37--If an application filed appears to claim substantially the same
invention for which a _caveat_ has been filed, the Commissioner of
Patents will notify the caveator to complete his application in three
months, and if upon the filing thereof it appears to be in conflict an
interference will be declared. If the caveator fails to complete his
application within the time designated, or such further time as for
cause shown may be granted to him, the Commissioner of Patents will
proceed to examine the first named application as if there were no
_caveat_.

38--Each party to the interference will be required to file a concise
statement under oath showing the date of his original conception of the
invention, of illustration by drawing or model, of its disclosure to
others of its completion and of the extent of its use.

39--Testimony in such cases may be taken orally before the Commissioner
of Patents, at such time as he may designate, or it may be taken by
commission according to the forms usual in the Courts of the Republic.

40--After the testimony is closed the case shall be carefully examined
by the Commissioner of Patents and adjudicated upon the proofs
presented.

CAVEATS.

41--A _caveat_ under the patent law is a notice given to the office of
the caveator's claim as inventor, in order to prevent the grant of a
patent to another for the same alleged invention upon an application