468 



NA TURE 



[September 12, 1S95 



are indissolubly bound up with the activities of the cell as a 

 li\nng organism, and that certain diseases, at least, are due to 

 the action of ferments in the living being. In 1S65 he showed 

 that the disease of silkworms, which was then undermining the 

 silk induslr)- in France, could be successfully combated. His 

 further researches into anthrax, fowl cholera, swine fever, rabies, 

 and other diseases, proved the theory that those diseases are 

 connected in some way with the introduction of a microbe into 

 the body of an animal ; that the vindence of the poison can be 

 diminished by cultivating the microbes in an appropriate 

 manner ; and that when the viiulence has lieen thus diminished 

 their inoculation will afford a protection against the disease. 



Meanwhile it had often been observed in hospital practice that 

 a patient with a simple-fractured limb was easily cured, whilst a 

 patient with a conijiound fracture often died from the wound. 

 Lister was thence led, in 1865, to adopt his antiseptic treatment, 

 by which the wound is protected from hostile microbes. 



This investigation, followed by the discovery of the existence 

 of a multitude of micro-organisms and the recognition of some of 

 them — such as the liacillus of tubercle and the comma bacillus 

 of cholera — as essential factors of disease ; and by the elabora- 

 tion of Koch and others of methods by which the several 

 organisms might be isolated, cultivated, and their histories 

 studied, have gradually built up the science of bacteriology. 

 Amongst later developments are the discovery of various so- 

 called antitoxins, such as those of diphtheria and tetanus, and 

 the utilisation of these for the cure of disease. Lister's treat- 

 ment formed a landmark in the science of surgery, and enabled 

 our surgeons to perform operations never before dreamed of; 

 whilst later discoveries are tending to place the practice of 

 medicine on a firm scientific basis. And the science of bac- 

 teriology is leading us to recur to stringent rules for the 

 Isolation of infectious disease, and to the disinfection (by super- 

 heated steam) of materials which have been in contact with the 

 suffeier. 



These microbes, whether friendly or hostile, are all capable of 

 multiplying at an enormous rate under favourable conditions. 

 They are found in the air, in water, in the soil ; but, fortunately, 

 the presence of one species apjxsirs to be detrimental to other 

 species, and sun.shine, or even light from the sky, is prejudicial 

 to most of them. Our bodies, when in health, appear to be 

 fumishe<I with special means of resisting attack, and, so far as 

 regards their influence in causing disease, the success of the 

 attack of a iMthrjgenic organism upon an individual depends, as 

 a rule, in part at least, upon the power of resistance of the 

 individual. 



But notwithstanding our knowledge of the danger arising 

 from a state of low health in individuals, and of the universal 

 prevalence of these micro-organisms, how careless we are in 

 guarding the health conditions of everyday life ! We have 

 ascertained that fathogenic organisms pervade the air. Why, 

 therefore, do we allow our meat, our fish, our vegetables, our 

 easily contaminated milk, to be exposed to their inroads, often 

 in the foulest Uxrallties? We have a.scertained that they pervade 

 the water we drink, yet we allow foul water from our dwellings, 

 our pigsties, our farmyards, to pass into ditches without previous 

 clarification, whence it flows into our streams and |x>llules our 

 rivers. We know the conditions of occupation which foster ill- 

 health. Why, whilst we remove outside sources of impure air, 

 do we [xrrmit the occu|iation of foul and unhealthy dwellings? 



The study of bacteriology has shown us that although some of 

 these organisms may be the accompaniments of disease, yet we 

 owe it to the operation of others that the refuse caused by the 

 cessation of animal and vegetable life is reconverted into food 

 for fresh generations of plants and animals. 



These considerations have formed a point of meeting where 

 the biologist, the chemist, the physicist, and the statistician 

 unite with the sanitary engineer in the applicition of the science 

 uf preventive medicine. 



ESCINBEKl.NG. 



Sewage Purification. 



The early re|>'irls lo the Association show that the laws of 

 hydrostatics, hydroilvnamics, and hydraulics necessary to the 

 supply and i ' ■ water through jiliK-s and conduits had 



long liecn in . the mathematician. Hut the modern 



.unitary cngiij in driven by the needs of an increasing 



popidatlon to call m the chemist and the biologist to help him to 

 provide pure water and pure air. 



The purification ami the utilisation of sewage occupied the 



NO. 1350, VOL. 52] 



attention of the British .\ssociation as early as 1S64, and between 

 1S69 and 1 8/6 a committee of the .Association made a series of 

 valuable reports on the subject. The direct application of 

 sewage to land, though eflectlve as a means of purification, 

 ent.ailed dltTicuUies in thickly settled districts, owing to the 

 extent of land required. 



The chemical treatment of sewage produced an effluent harm- 

 less only after having been passed over land, or if turned Into a 

 large and rapid stream, or into a tidal estuary : and it left behind 

 a large amount of sludge to be dealt with. 



Hence It was long contended that the simplest i^lan in favour- 

 able localities was to turn the sewage Into the sea, and that the 

 conse()uent loss to the hind of the manurlal value In the sewage 

 would be recouped by the Increase in fish-life. 



It was not till the chemist called 10 his aid the biologist, and 

 came to the help of the engineer, that a scientific system of 

 sewage purification was evolved. 



Dr. Frankland many years ago suggested the intermittent 

 filtration of sewage ; and Mr. Baldwin Latham was one of the 

 first engineers to adopt It. But the valuable experiments made 

 in recent years by the State Board of llealtli in Massacliusetts 

 have more clearly explained to us how tiy this system we may 

 utilise micro-organisms to convert organic Imiiurity In sewage 

 into food fitted for higher forms of life. 



To effect this we require, In the first place, a filler about five 

 feet thick of sand and gravel, or, Indeed, of any material which 

 affords numerous surfaces or open pores. Secondly, that after a 

 volume of sewage has passeil through the filter, an Interval of 

 time be allowed. In which the air necessary to support the life of 

 the micro-organisms Is enabled to enter the pores of the filter. 

 Thus this system is dependent upon oxygen and time. Under 

 such conditions the organisms necessary for purification are sure 

 to establish themselves In the filler before it has been long in use. 

 Temperature Is a secondary consideration. 



Imperfect purification can invariably be traced either to a 

 lack of oxygen In the pores of the filter, or to the sewage passing 

 through so quickly that there Is not sufficient time for the ncces- 

 saiT processes to take jilace. .\nd the power of any material to 

 purify either sewage or water depends almost entirely upon its 

 ability to hold a sutiicient proportion of either sewage or water ire 

 contact with a proper amount of air. 



Smote Abatement. 

 Whilst the sanitary engineer has done much lo improve the 

 surface conditions of our towns, to furnish clean water, and to- 

 remove our sewage, he has as yet done little to jHirlfy town air. 

 Fog is caused by the floating particles of mailer In the air 

 becoming weighted with aqueous vapour ; some particles, such 

 as salts of ammonia or chloride of sodium, have a greater affinity 

 for moisture than others. You will suffer from f.ig so long a.s 

 you keep refuse stored In your towns to fiirnlsh ammonia, or so 

 long as you allow your street surfaces to supply dust, of which 

 much consists of jiowdered horse manure, or so long as you senJ 

 the products of combustion Into the atmosphere. Therefore, 

 when you have ailopted mechanical traction l^or vehicles In your 

 towns, you may largely reduce one cause of fog. And if you 

 diminish your black smoke, you will diminish bl.tck fogs. 



In manufactories you m.ay prevent smoke either by care in 

 firing, by using smokeless coal, or by washing the soot out i>l 

 the products of consumption in its jrassage along the flue leading 

 to the main chimney-shaft. 



The black smoke from your kitchen may be avoided by the 

 use of coke or of gas. But so long as we retain the hygienic 

 arrangement of the oj^n fire in our living-rooms I despair of 

 finding a fireplace, however well constructed, which will not be 

 used In such a manner as to cause smoke, unless, indeed, the 

 chinmeys were reversed and the fumes drawn into siune central 

 shaft, where they might be w.ashed befi>re being passed Into the 

 atmosphere. 



Electricity as a warming and cooking agent wnulil be con- 

 venient, cleanly, and ecommilcal when generated by water jKiwer, 

 or possibly wind power, but it is at present loo dear when it has 

 to l)e generateil by means of coal. I can conceive, however, 

 th.at our descendants may learn so lo utilise electricity thai they 

 In some future century may be enabled by Its means to avoid 

 the smoke in their towns. 



Mechanical Engineering. 

 In other branches of civil and mech.anical engineering, the 

 reports In 1831 and 1832 <m ihe .state of this science show that 



