June 7, [889.] 



SCIENCE. 



437 



Filters. — Dr. Currier of New York has recently been engaged 

 in examining into the efficacy of filters and other means employed 

 to purify drinking-water. His paper on the subject is published in 

 the Medical News. He summarizes the result of the investigation 

 as follows : Boiling sterilizes water, and within thirty minutes will 

 have killed harmful bacteria. Drugs and other agents acting chem- 

 ically, if used in amounts which are commonly safe, do not sterilize 

 water. The prolonged heat which water undergoes in the usual 

 process of distillation destroys all germs which may be in the water 

 undergoing the process. Ordinary filters, even if satisfactory as strain- 

 ers, fail to remove all bacteria from drinking-water. So far from les- 

 sening the number in the original water, the filtering substance may 

 allow a more rapid multiplication than these micro-organisms 

 would ordinarily undergo in the unfiltered water on standing ; and 

 the germs of disease, even if held back by the filtering substance, 

 may be harbored in all filters. The finer the substance through 

 which the water passes, and the lower the pressure, the more per- 

 fect is the action of the filter in holding back the bacteria. Of all 

 substances thus far furnished for domestic filters, porous rebaked 

 porcelain, carefully selected, has been found to be the best. If 

 thick and strong enough to allow the use of a large surface, and 

 the substance remain perfect (without flaw or break), this may 

 yield a fair flow of clear water, free from all bacteria ; yet, under 

 our ordinary Croton pressure of one atmosphere or less, this yield 

 is only in rapid drops, unless the apparatus be complex. To insure 

 the permanency of this action, the filter should be occasionally 

 sterilized throughout, by steaming or by other means ; for, under 

 prolonged pressure, various kinds of bacteria can go through, and 

 in the copious organic matter collected on the filter some harmful 

 micro-organisms can retain a high degree of vitality for weeks 

 longer than they have ever been found to live in pure water. 

 Where filtering is really necessary, it is in general best for the com- 

 munity that it be done carefully on a large scale through sand-beds 

 upon which a fine layer of organic and inorganic matter is expressly 

 produced by sedimentation, because of its valuable action in hold- 

 ing back the great majority of the bacteria. A bad water filtered 

 is less desirable than a pure water in its natural state. When, 

 therefore, filtration is employed because of real danger of infection, 

 the filtered water should, as a rule, be furthermore boiled, as the 

 entire absence of sediment and cloudiness does not insure that the 

 bacteria of disease may not have made their way through the filter. 



Asphyxiation by Illuminating-Gas. — At a recent meet- 

 ing of the American Gaslight Association of Toronto, the following 

 rules were given, to be followed when men are overcome by gas : 



1. Take the man at once into fresh air. Don't crowd around him. 



2. Keep him on his back. Don't raise his head nor turn him on 

 his side. 3. Loosen his clothing at his neck and waist. 4. Give a 

 little brandy and water, — not more than four tablespoonfuls of 

 brandy in all. Give the ammonia mixture (one part aromatic 

 ammonia to sixteen parts water) in small quantities, at short inter- 

 vals, — a teaspoonful every two or three minutes. 5. Slap the face 

 and chest with the wet end of a towel. 6. Apply warmth and fric- 

 tion if the body and limbs are cold. 7. If the breathing is feeble 

 or irregular, artificial respiration should be used, and kept up until 

 there is no doubt that it can no longer be of use. 8. Administer 

 oxygen. 



Cancer Contagion. — The contagiousness of cancer is still a 

 mooted question. Dr. Arnaudet, in La Normajtdie MMicale, main- 

 tains the affirmative of the question, and gives the following facts 

 to support his views : At Saint-Sylvestre-de-Cormeilles, which has 

 a population of about four hundred persons, there were seventy-four 

 deaths in eight years. Of these, eleven were from cancer. In the 

 neighboring villages of Normandy, although exact figures are want- 

 ing, the death-rate from cancer is said to be nearly the same. Of these 

 eleven cases, six occurred within a limited area, and the order of 

 their occurrence was such as to suggest a possible connection 

 between them. The first case was that of a man living in an ele- 

 vated portion of the hamlet ; the next case was a man living on the 

 side of the hill below the first ; then three cases occurred almost 

 simultaneously in persons livmg close together in the valley at the 

 foot of this hill ; and the sixth patient was a near neighbor of the 

 first, on the plateau above the valley. In none of these cases could 



any history of heredity be obtained, and they were all free from the 

 reproach of alcoholic addiction. In five of the cases the cancer 

 was seated in the stomach, and in the sixth the location of the 

 disease was in the neck. Dr. Arnaudet believed that the germ of 

 the disease, microbial in its nature, was carried in the water. None 

 of the patients drank water, but they were all moderate consumers 

 of cider, and that was the beverage that the author accused of be- 

 ing the carrier of the contagion. In making cider, the inhabitants 

 of that region added water taken from the swampy ground ; and 

 the darker the color of the water, consequently the more impure, 

 the higher it was esteemed as a diluent of the apple-juice. 



NOTES AND NEWS. 



The invention and development of electric welding of solid 

 bodies by Professor Elihu Thomson has been followed by a method 

 of making endless pipes by the adaptation of the discovery to that 

 purpose. This has apparently been done by Mr. Elias E. Ries of 

 Baltimore. The smooth interior of the pipe is secured by the use 

 of a removable refractory core, made of some insulating material, 

 or the same object is attained by subjecting the interior of the pipe 

 while being welded to compressed air or fluid pressure. 



— In a description of the Calais harbor works in Engmeering, 

 occurs the following reference to the use of the water-jet for sink- 

 ing the piles of the protecting dike or dam of the sluicing-basin : 

 " The engineer in charge of this portion of the work sunk all the 

 piles with the help of water-jets, — a system which has, of course, 

 been in use for many years for sinking cylinders and iron piles, 

 but which, we believe, had never been previously employed in this 

 particular manner. The first trials were made in 1877, and the 

 results obtained were so remarkable that the method was followed 

 throughout nearly the whole of the work. Before this means was 

 tried, the operation of driving a panel of sheet piling 9 feet high 

 and 6 feet wide required 900 blows from a 1,300-pound weight, 

 and the average time occupied was 8J hours. The sand offered 

 so much resistance, that the thickness of the piling had to be in- 

 creased from 3-inch to 5-inch, and even then the wood was fre- 

 quently broken. All these difficulties disappeared with the intro- 

 duction of the water-jet, which was forced into the sand by hand- 

 pumps through a i-inch nozzle connected to rubber tubes. Much 

 wider panels could be lowered in this manner, and the time of sink- 

 ing was reduced to about one hour, while in many cases the 

 operation was completed in 15 minutes. The number of blows 

 from the falling weight never exceeded 50, and were only necessary 

 to overcome the friction between the adjoining panels, which were 

 tongued and grooved so as to make a tight joint. As a rule, the 

 weight of the 1,300-pound tup resting on the head of a lo-foot pile 

 sufficed to drive it almost instantly into its place." 



— An international congress of agriculture and forestry will be 

 held in Vienna during the summer of 1890. 



— We learn from the American Lancet that since its establish- 

 ment the Minnesota Board of Medical Examiners have had eighty- 

 six applications for examination for a license to practise medicine. 

 Of these, six were refused admission because they had not taken 

 three full courses of lectures of six months each. Of the eighty 

 entering the examination, fifty-one were found able to pass 

 the same, and twenty-nine were rejected as not possessing the 

 knowledge of medicine required by the board. Of those passing, 

 forty-nine are regular, and two are homoeopathic. Of those re- 

 jected, eighteen were regulars, eight homoeopaths, and three eclec- 

 tics. Students from two-term medical colleges cannot even get a 

 chance to be examined in Minnesota. 



— An improved method of producing phosphorus has lately been 

 patented in Paris. It consists, as described in The Engiiteerittg 

 and Mining Journal, in treating bones or powdered mineral with 

 nitric acid. A large proportion of the calcium is then removed 

 from the solution — on the addition of potassium sulphate to liquid 

 — in the form of calcium sulphate. The liquid then contains 

 phosphoric acid and potassium and calcium nitrates. After re- 

 moving the precipitated calcium sulphate by means of filtration, 

 sufficient mercurious nitrate is added to precipitate the phosphoric 

 acid as mercury phosphate. The phosphate of mercury so ob- 



