The distribution of micro-organisms in air / by Percy F. Frankland ; communicated by E. Frankland.

  • Percy F. Frankland
Date:
1885
Catalogue details

Licence: Public Domain Mark

Credit: The distribution of micro-organisms in air / by Percy F. Frankland ; communicated by E. Frankland. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    1886.] The Distribution of Micro-organisms in Air. through which several of these tubes can protrude, their ends being then covered by a glass shade externally coated with cotton-wool or any other non-conducting material. By contriving this simple ar- rangement I was able to keep every portion of tbe tubes in an atmo- sphere of steam, whilst no condensed water could find its way into the tubes. Fig. 1. I have found it very necessary not to overdo the steaming, as the melting point of the gelatine is considerably reduced by its being prolonged, and in these experiments it is of the greatest importance that the gelatine should be capable of resisting the temperatures which are incidental to the experiments, and which are encountered in travelling with the apparatus. If the gelatine be too sensitive to heat many experiments may be entirely lost, and the time and labour spent upon their careful execution wasted. I would therefore recom- mend that both in the preparation and in the sterilisation of the gela- tine-peptone used in these tubes, the steaming should be reduced to a minimum consistent with sterility. When finally sterilised, and whilst the gelatine is still fluid, the tube is held horizontally under a cold-water tap, being simultaneously rotated and moved backwards and forwards, so that uniform cooling is effected. As the gelatine approaches its solidifying point it be- comes more and more viscid, and gradually adheres to the surface of the tube, so that with a little management the whole interior can be uniformly coated. In this operation contact between the gelatine and the cotton-wool plug in the small tube at the end must be care- fully avoided, otherwise when cold the tube may become blocked up. The tube after being preserved for some time to insure sterility, is then fit for use.