A process for the preparation of a stable solution of semitrichinoyl is disclosed. A solution of rhodizonic acid and a solution of trichinoyl octahydrate is mixed and subjected to the action of light. The solutions of rhodizonic acid and trichinoyl occtahydrate have the same molarity, whereby a solution of semitrichinoyl is formed. Pursuant to a preferred embodiment: (a) an aqueous solution containing about 1% by weight of inositol is chlorinated in the presence of light at a temperature of between about 40.degree. C. and 60.degree. C., (b) the reaction solution (RL) thus obtained is filtered, (c) the filtrate is neutralized with a solution of sodium hydrogen carbonate and, by adding a small amount of barium chloride, precipitating the low-molecular polymerized barium salt compounds (R2), (d) adding again barium chloride to the filtered-off solution, and (e) then adding to the precipitate (R3) thus obtained a sulfuric acid produced by the reaction of (1) one part of a mixture of acetaldehyde and ethyl alcohol at a ratio of 1:5, and (2) one part of a mixture of acetaldehyde and ethyl ether at a ratio of 1:8, with (3) 10 parts of concentrated sulfuric acid while heat is supplied.
