. Public health laboratory work, including methods employed in bacteriological research, with special reference to the examination of air, water and food contributed . Fig. ioi.—Chamberlands filter. temperature causing the agar to dissolve readily, andrendering it very easy to filter; it also very rapidlysterilises potatoes. Filtration in the cold.—It is often required toseparate the products of metabolism from cultivations ofmicro-organisms, without subjecting them to the actionof heat. For this purpose filters of (unglazed) porcelainor of porous earth are employed. The porcelain isusually in
. Public health laboratory work, including methods employed in bacteriological research, with special reference to the examination of air, water and food contributed . Fig. ioi.—Chamberlands filter. temperature causing the agar to dissolve readily, andrendering it very easy to filter; it also very rapidlysterilises potatoes. Filtration in the cold.—It is often required toseparate the products of metabolism from cultivations ofmicro-organisms, without subjecting them to the actionof heat. For this purpose filters of (unglazed) porcelainor of porous earth are employed. The porcelain isusually in the form of a hollow cylinder, through which 432 LABORATORY WORK. the liquid to be filtered is either forced or sucked bymeans of a pump. There are numerous forms of thesefilters, of which the Chamberland model is well known,fig. loi. Such a filter may readily be attached to anordinary water tap when it is desired to obtain purewater. With the same end in view a much more. Fig. I02.—Porcelain material to be filtered is placed in the upper receiver and thensucked through the porcelain bougie ; the filtrate collects in the testtube immediately beneath the latter. porous substance of diatomaceous earth is made intocylinders, to which are attached indiarubber tubes ; thecylinders are simply placed in water, and by a syphonaction the water slowly passes through. A simpleporcelain filter for cultures is seen in fig. 102. Porousfilters, like the above, are best cleaned by calcining. NUTRIENT MEDIA. 433 Sterilisation at temperatures between 60° and 100° C.—Inthe case of blood serum, it is desirable to sterilise at atemperature just below that at which the albumins co-agulate. For this purpose an incubator, water bath,oven, or the special serum steriliser of Koch, may beused. The sterilising has to be performed severaltimes, and the process watched. To obviate the ne-cessity of sterilisation, blood may be received directlythrough a sterilised ca
Size: 976px × 2561px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, bookpublisherphiladelphiablakis
