The phrase "in certain proportion" is correct and can be used in written English.
It is often used to indicate that something has been distributed or measured accurately and reliably. For example, "The ingredients were measured in certain proportion to ensure an even consistency."
Research has shown that such alloys as lanthanum-nickel in certain proportions will reversibly dissolve or release hydrogen in proportion to changes in pressure and temperature.
This study is an experimental research on the mechanical features of hybrid fiber added concretes which are obtained using steel fibers and polypropylene (PP) fibers together in certain proportions.
tity, or to require him to select part out of a greater quantity; and when the goods are to be shipped in certain proportions monthly, the seller's failure to ship the required quantity in the first month gives the buyer the same right to rescind the whole contract that he would have had if it had been agreed that all the goods should be delivered at once.
The most widespread activation method is simultaneous supply of incomplete combustion of natural gas and steam in certain proportions into the activation apparatus.
In some instances, the electors appointed by legislative choice have been taken from the body of the people at large without previous limitation; in other instances, from a restricted list, nominated in certain proportions by each House of the Legislature, respectively.
Al aleph the Arabic equivalent of the letter A has to be drawn in certain proportions, or technically it's not calligraphy.
In these cases, in order to be effective in the wild, relevant components must all be present in the pheromone plume in certain proportions, and recognising the correct ratio of pheromone component concentrations becomes critical for the mating success of the male.
