Originally published in The British Medical Journal on March 6, 1886.

Sir, --In the Journal of February 27th, appeared a short article giving an account of the results obtained by Horn, working under the direction of Professor FOrster, of Amsterdam, with the Pasteur-Chamberland filter. As the reader might gather from the concluding lines of your article, that some difficulties attend the use of this filter, I venture to correct a possible misconception. This admirable invention appears to me to realize pratically the ideal of a filter, for it removes all living forms and their germs, without affecting the chemical composition of the water. Having employed one of these filters in my house during the last three months, I have become convinced that they have only to be known in order to replace all other filters.

As was mentioned in your article, the water to be filtered is forced under pressure through a tube of unglazed porcelain, and in this process is so freed from organic germs that, as was first found by M. Pasteur, and confirmed by Dr. Percy Frankland, and by Horn, it is perfectly sterilized. In order to demonstrate the fact, the porcelain tube must, of necessity, be first sterilized by the action of heat, so as to destroy the germs accidentally adhering to the inside of the filter; and this is a procedure which can only be practiced by skilled persons provided with suitable appliances. Where pure water is needed for domestic purposes, however, this preliminary sterilization by heat is altogether unnecessary, for the object is to remove all germs which may accidentally have become mixed with it from the water which passes through; and this will be effected as perfectly by an unsterilized tube as by one which has been sterilized.

The Pasteur Pipet was a basic instrument that played a crucial role in the experiments of Louis Pasteur experiments. Once the concept of Germ Theory was clearly established, the necessity to keep everything sanitized and free of germs was central to all experiments. Therefore, the Pasteur Pipet was developed to ensure liquids could be removed or transferred without introducing foreign elements that could possibly pollute the contents.

The pipet used during Louis Pasteur's time was a simple glass tube with cotton wadding stuffed into one end. The cotton allows air to pass into the pipet's glass tube, but is fine enough to filter microbes from the air to ensure the content will not become contaminated. The opposite end of the pipet was heated until the glass becomes maleable and then extended, creating an elongated tip. The tip is then severed, creating an extremely small opening into which the liquid can enter. This video below demonstrates an older method for manufacturing the Pasteur Pipet.