Cookery for every household

It will be easier, however, to describe the steriliser after explaining the process of sterilisation. Sterilisation is briefly this — to make sterile or deprive of vitality the bacteriological germs which cause decay and putrefaction in fruit and vegetables, as well as in other forms of food. If these germs are destroyed and kept from approaching the sterilised object again, it will keep perfectly sound and good for a considerable time, possibly an unlimited time. This result is brought about by the following process. The article (fruit or vegetable) to be sterilised is packed into a glass jar or bottle, which is then filled with cold water and closed either by a metal or glass cap fastened by a clip or a screw ; the bottles are placed in a vessel containing cold water ; heat is applied in one form or another, and the temperature of the water bath is slowly raised until it is sufficiently high inside the glass jars to kill the bacteriological germs. The exact degree of heat required to destroy the germs varies considerably according to the object which is being sterilised ; in fact, some fruits and some vegetables require three or four successive sterilisations (by which first one bacteriological family and then another are destroyed) to bring about the required conditions. The hot air and steam, by which the bottles in the steriliser or other vessel are now surrounded, causes the water or juice inside the bottles to get hot and expand, until it reaches the air-tight capsule or cover. The requisite temperature is sustained for some time at an equal height until the process is complete (this can be determined to a nicety by the fixed thermometer), and the bottles are either lifted out. and put into a cool place, or else cold water is turned into the machine whilst the bottles are in it (the hot water having been previously drawn off). With the decreasing temperature the vacuum is created, and unless the caps or tops are imperfect or imperfectly adjusted, and so admit the air, the contents of the jar, as before stated, will keep for any length of time, because germs do not incubate in a vacuum. This, then, is the theory carried out by the process of sterilisation, li sufficiently complete, and, as before stated, the requisite temperatures for the different fruits and vegetables have been proved, and these tempera- tures have been registered by a thermometer, the vacuum is attained and the germs made sterile. It may chance, however, that the rubber bands or the caps are not placed on the bottles quite evenly, or, if the cap is screwed, that the screw ring is not quite perfect ; then, if from one cause or another air is admitted, as a certain consequence the vacuum is destroyed, the germs come into life, and immediately begin to cause decay and decomposition or fermentation. If this is not at once noted, and the batch of bottled fruit resterilised and re-capped, it will all go bad. In the Mercia Patent Steriliser every attempt has been made to put upon the market a steriliser Mercia Steriliser which is the outcome of practical experience, presented in a portable, tangible, practical, and workmanlike form, and at a price which brings it within the reach of all who are taking the bottling of fruit year by year seriously.