. Public health laboratory work, including methods employed in bacteriological research, with special reference to the examination of air, water and food contributed . hould not exceed 9 per cent, in a puresample. The sand or earthy matter generally gainsaccess in the following manner;—The berries areallowed to fall from the trees on to the ground, wheremany of their minute furrows become filled with thesoil; or by the wearing of the stones between whichthey are ground the powder acquires some sand—3*27 ^]^ LABORATORY WORK. per cent, is a reasonable margin to allow for the pre-sence of this un
. Public health laboratory work, including methods employed in bacteriological research, with special reference to the examination of air, water and food contributed . hould not exceed 9 per cent, in a puresample. The sand or earthy matter generally gainsaccess in the following manner;—The berries areallowed to fall from the trees on to the ground, wheremany of their minute furrows become filled with thesoil; or by the wearing of the stones between whichthey are ground the powder acquires some sand—3*27 ^]^ LABORATORY WORK. per cent, is a reasonable margin to allow for the pre-sence of this unavoidable sandy matter. A rather rough but serviceable method, recommendedby Neuss, and quoted in Parkes Practical Hygiene,consists in covering the pepper with concentratedhydrochloric acid, when, if the sample is pure pepper,it becomes of an intense and uniform yellow, and mostof the foreign ingredients remaining uncoloured, readilybetray their presence. Unlike mustard, pepper contains starch. Micvoscopical characters of pepper.—A transverse sectionof the black pepper berry shows the following notablepoints:—Starting from the cortex, most externally is. Fig. 86.—The cells forming the central part of the pepper-berry (X loo). a layer two or three cells deep, arranged vertically, andvery much resembling in appearance the bean-starchgranules, , ovoid, with a central linear hilum crossedby transverse markings; next follows an ill-definedlayer of elongated cells arranged transversely to theforegoing, and then a sort of irregular reticular tissuecontaining oil globules ; more internally still, a welhdefined single layer of large vertical more or less flask-shaped cells appears. The rest of the interior of theberry consists of flattened angular cells, dovetailed intoeach other, and containing starch. White pepper is simply the central part of the berry. SUGAR. 377 Sugar. The sugar of commerce is almost entirely cane sugar—very little glucose coming into ordinary domes
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