A Still for the Continuous Production of Glass—Distilled Water. ∗

Abstract

It is frequently necessary in biological work to have a continuous supply of glass—distilled water available. The apparatus described here has proven to be entirely satisfactory for this purpose. It has been in operation in our laboratories for over a year, 24 hours a day, without a serious breakdown. During this time it has produced on the average 70 liters of glass—distilled water per day. The design is flexible and may be adapted to larger or smaller needs. The only manual labor involved in operating the still consists of filling the storage flasks and emptying the receiver flasks.

The still is shown in Fig. 1. A few features of the construction need to be emphasized. For proper operation the upper storage bottle should be tightly sealed. The condenser D on the siphon tube will condense all steam formed in this tube, thereby preventing breaking of the siphon. There should be a rapid flow of cooling water through both of the condensers. The Allihn condenser L was found to be the most efficient condenser for the purpose. The close clearance between the bulbs and the jacket produces high cooling—water velocities. The use of a Graham condenser is to be avoided due to the large back pressure produced. The vent tube on the receiver is ca 3 cm below the outlet of the condenser and leads into a drain. This is to prevent the closing of the system when the receiver is full. The outside diameter of the tubes used for the siphon and the vent system should be 8 mm. The vent on the receiver flask can either drain into the sink, or may lead to a second storage bottle. In order to prevent contamination with grease, none of the joints is greased.