LABORATORY WORK BY HENRY R. KENWOOD, M.B. D.P.H., F.C.S. INSTRUCTOR IN THE HYGIENIC LABORATORY, UNIVERSITY COLLEGE, AND ASSIS- MENT, SOUTH KENSINGTON, ETC. INCLUDING METHODS EMPLOYED IN BACTERIOLOGICAL RESEARCH, WITH SPECIAL CONTRIBUTED BY RUBERT BOYCE, M.B. ASSISTANT PROFESSOR OF PATHOLOGY, UNIVERSITY COLLEGE WITH ILLUSTRATIONS PHILADELPHIA P. BLAKISTON, SON & Co. No. 1012 WALNUT STREET 1893 Ар X37 1893 PREFACE. THE matter contained within these pages is broadly that which is taught, under the direction of Professor Corfield, in the Practical Hygiene Course at University College. It is hoped that the book will prove of value to those interested in Public Health, and to those seeking Public Health degrees, and that it may be read along with the many excellent works upon Hygiene and Public Health which are now in circulation, but which of necessity deal with the subject of hygienic analyses in far too cursory a manner. An effort has been made to convey to the reader, in a concise and practical form, the knowledge necessary to enable him to make those analyses which may be fairly considered to be included within the domains of practical hygiene. To treat the subject exhaustively would necessitate a very bulky volume, and those who recognise the breadth of subject matter embraced by the title "Public Health Laboratory Work," will appreciate that it has been found necessary, in the present volume, to avoid all discursive matter save what is required to make the rationale of a process evident, and where there are several processes in vogue to one common end, to select that one which experience has taught to be at the same time the most simple, ready and efficient-to the exclusion of all others. It has not been an easy task, in every case, to decide as to what should be included and what omitted. 8944 There are, for instance, several recent and somewhat improved methods of estimating the carbonic acid in air, but the process of Pettenkofer has become what one may term "classical," and is that which is still generally asked in Public Health Examinations; and since the method is sufficiently accurate, when carefully performed, for all practical purposes, it was thought advisable to introduce it to the exclusion of others. The subject of hygienic analysis will be seen to dovetail itself into the work of the Public Analyst, but not to such an extent, it is held, as to render that officer any the less essential to a district. The writer acknowledges his great indebtedness to the useful contribution on bacteriological methods by Dr. Boyce, for he recognises how much this enhances the value of the work; he desires also to express his thanks for many kind and valuable suggestions from Professor Corfield, Dr. Louis C. Parkes and Dr. Braga. He is further indebted to Dr. Louis C. Parkes for the use of figures 51, 52, 55, 58, 60 to 67, 69 to 74, 81, 82, 84, 88, 89, 90, taken from his "Hygiene and Public Health." University College, W.C. H. R. K. |