This section is from the "Henley's Twentieth Century Formulas Recipes Processes" encyclopedia, by Norman W. Henley and others.
Add 2 tablespoonfuls of bakers' yeast to 1 pint of rich milk, which has been slightly warmed, stirring well together and setting aside in a warm room in a pitcher covered with a wet cloth for a time varying from 6 to 12 hours, according to the season or temperature of the room. Take from this, when curdled, 6 tablespoonfuls, add to another pint of milk, and again ferment as before, and continue for five successive fermentations in all, when the product will have become free from the taste of the yeast. As soon as the milk thickens, which is finally to be kept for use, it should be stirred again and then put into a refrigerator to prevent further fermentation. It should be smooth, of the consistence of thick cream, and of a slightly acid taste.
The milk should be prepared fresh every day, and the new supply is made by adding 6 tablespoonfuls of the previous day's lot to a pint of milk and proceeding as before.
The curd is to be eaten with a spoon, not drunk, and preferably with some bread broken into it. It is also sometimes eaten with sugar, which is said not to impair its digestibility.