622 



NA TURE 



[April 25, 1901 



of the conjunctiva of the eye and other mucous membranes with 

 liquids not strong enough to injure the Hving cells of the skin. 

 The best method of antiseptic treatment of the intestine, merely 

 relative as its efficacy might be, was now recognised in the use 

 of drugs which produced frequent and abundant evacuation. 



How were we to square the conviction that so many of the 

 microbes usually found in the body were injurious with the 

 argument, drawn from the work of Darwin, that if our microbes 

 are so dangerous they ought long ago to have been eliminated 

 simply by the operation of natural selection ? One observed 

 constantly that not merely natural characteristics unfavourable 

 to their possessor's life, but even organs which had merely 

 ceased to be useful to him, disappeared more or less completely. 

 To bring out more clearly this paradoxical aspect of the sur- 

 vival of our microbes, most of which were not merely useless 

 but unquestionably injurious, he would draw attention to the 

 fact that the very organs of the body which sustained this flora 

 were themselves for the most part either useless or injurious to 

 health and life. They would remember that the ducts of 

 the capillary follicles in the skin were the seat of a microbian 

 vegetation often composed largely of microbes capable of pro- 

 ducing more or less serious disease. Well, those follicles were 

 useless organs, and represented merely what was left of the 

 hair that covered the skin of animals who were our ancestors. 

 In the digestive apparatus of man, the part of the body richest 

 in microbes, there were also to be found parts which, to say 

 the least of them, were now useless. The vermiform appendix, 

 for instance, was the remains of an organ which was more fully 

 developed in our animal forefathers ; in the anthropoid apes it 

 was already found in the process of reduction. Even the 

 stomach, that organ which might seem so indispensable for 

 digestion and the normal existence of man, was in reality 

 nothing but a large reservoir for food, a reservoir which could 

 without serious inconvenience be dispensed with. There were 

 at that moment four persons living without stomachs, and thus 

 furnishing a strong argument against the utility of that organ. 



Of all the parts of our digestive system it was certainly the 

 small intestine alone that was indispensable to the continuance 

 of life. And yet in man, who could support himself on food 

 easily digestible, the small intestine was disproportionately fully 

 developed. Instead of having it between i8 and 21 feet long, 

 man might do with one-third of that length. Kukula reported 

 a case in which he had removed almost two-thirds of the small 

 intestine with the greatest advantage to the patient. In one 

 case Korte had removed, together with part of the small 

 intestine, the greater part of the large intestine, leaving only 

 the terminal section. As a result of this operation the patient 

 had been completely cured. Pie could cite other cases of 

 successful surgical operations to prove the uselessness of the 

 large intestine to human beings. In one case the whole of the 

 large intestine had atrophied of itself, without operation, in 

 consequence of a fistula, without interfering with the active life 

 of the subject. The sum of all this was that we possessed a 

 voluminous and highly developed organ, the large intestine, which 

 fulfilled no useful function and bred a very copious and varied 

 mass of microbes, capable of injuring us through their poisons. 



In face of thisf act it remained to ask what the large intestine 

 was, what its origin and the reason of its existence. The 

 history of the capillary jfollicles was comparatively simple, for 

 they were the surviving traces of hair which had protected 

 from the cold the animals from which man was descended. The 

 large intestine, on the contrary, was no mere relic, but an 

 organ highly developed. It was, as a rule, found only in the 

 mammiferous animals, and not in birds, reptiles, or others of 

 the lower vertebrates. Dr. Metchnikoff went on to trace in some 

 detail the development of the large intestine to the prevalence 

 of certain special conditions in the life of herbivorous vertebrate 

 animals capable of running at great speed, conditions no longer 

 present in the life of their descendants, and no longer calling 

 for the peculiar organisation developed to meet them. The 

 slow tendency of evolution to bring about the atrophy of such 

 organs or characteristics might, however, be assisted by medi- 

 cine and surgery, medicine coping more effectually with the 

 noxious microbes and their effects, while the progress of sur- 

 gery had already brought it within its power to remove by 

 operation organs or parts of organs propitious to the growth 

 of the "flora." 



Dr. Schunck proposed, and Prof. Hickson seconded, a vote of 

 thanks to the lecturer, and the resolution was carried by 

 acclamation. 



NO. 1643, VOL. 63] 



MODERN METHODS OF GAS MANUFAC- 

 TURE, 



A PAPER on modern practice in the manufacture and distribu- 

 ■^ tion of illuminating gas was read by Mr. Harry E, 

 Jones at the meeting of the Institution of Civil Engineers 

 on April 16, and some of the points dealt with are here 

 summarised. 



The author remarked that improved returns from residuals at 

 gasworks have been obtained by giving greater attention to the 

 saving of fuel by the use of generator furnaces ; by manufactur- 

 ing the ammonia at the gas-works ; by the preparation of 

 cyanogen ; and by the more extensive application of the 

 antiseptics which are largely and cheaply produced from the 

 tar. 



The enrichment of gas, by reducing the return from residuals, 

 has adversely affected the progress of gas-supply. The materials 

 needed are all costly, and yield no return. Moreover, with 

 incandescent burners, the cost of enrichment is wasted. Of the 

 means of enrichment available, carburetted water-gas is pre- 

 ferred for cheapness and permanency. The advantages of this 

 method are : facility for rapid and considerable addition to the 

 output of gas, and for suspension of such additional supply 

 without consequent expense ; complete control of illuminating 

 power over a wide range ; avoidance of excessive accumulation 

 of coke in winter ; prevention of the deposit of naphthalene in 

 the distributing mains and services, which formerly caused great 

 loss and inconvenience ; and reduction of space required by the 

 plant, and for storage of materials. It was pointed out, however, 

 that it is chiefly for mid-winter use, to relieve the strain on the 

 coal-gas plant and the drain on the collieries, and to meet 

 fogs and sudden climatic changes, that the system is profitable, 

 as the price of oil advances with the price of coal, and to a 

 figure that, having regard to value of residuals, cannot be paid 

 without loss. During the winter of 1900-1901 the price of oil 

 was practically prohibitive of its use, except for necessary 

 enrichment or emergency use. Should it, however, be possible 

 to supply unenriched water-gas, which, with the Welsbach 

 burner, gives equal illuminating power, then the use of oil could 

 be dispensed with and the combined coal- and water-gas pro- 

 cesses could be carried on with a large saving and would enable 

 the price of gas to be lowered by between is. 2d. and \s. 8d. per 

 1000 cubic feet. 



In purifying-plant the author recommended the abandon- 

 ment of the old hydraulic seal, which is unstable, costly and very 

 perishable. In his practice the entire cover is removable, being 

 very light and held down by small bolts at the margin, and by 

 bolts passing through both cover and floor and spaced at equal 

 distances. The vessels are 8 feet deep and are arranged in 

 groups of five worked in ordinary sequence, having both lime 

 and oxide of iron in each. This system fulfils without nuisance 

 all the requirements of the sulphur-purification demanded by the 

 London Gas Referees without the cost, risk and space of the 

 system of three separate groups previously necessary, in order, 

 for carbonic acid, carbon bisulphide and sulphuretted hydrogen. 

 For condensers the author prefers horizontal tubes, in which the 

 tar and gas are cooled together, which have been found to remove 

 naphthalene. Coke scrubbers are simplest and cheapest, and in 

 practice more than secure the degree of purification from 

 ammonia exacted by the London Gas Referees, and, by the 

 ammonia retained, purifies the gas also from carbonic acid 

 and sulphur. The residuals of gas are useful in purification, and 

 a cycle of reactions was traced in the processes of manufacturing 

 sulphate of ammonia by sulphuric acid made partly from the 

 sulphur in the ammoniacal liquor and partly from that in the 

 residual spent oxide of iron from purifiers. 



The pressure for distribution of gas is usually 3 inches to 4 

 inches head of water, but Mr. C. C. Carpenter has for some 

 time been delivering by means of Sturtevant fans, at pressures- 

 between 12 inches and 18 inches. In America distribution has 

 been accomplished over long distances by employment of pres- 

 sures of several pounds per square inch. Service pipes are now 

 laid in steam-tubing 30 per cent, thicker than gas-tubing ; they 

 are coated with pitch before filling the ground in, and their 

 life has thus been extended from 12 years or 14 years to more 

 than 20 years. Meters of the "dry" form are now invariably 

 employed, which, if examined periodically, at intervals of 6 or 

 8 years, can be maintained fairly accurate ; by improvements 

 in manufacture their life has been increased from 12 years to 

 nearly 20 years. 



