For a third time and by altogether different means, it was demonstrated that the air was the bearer of these germs. The whole atmosphere was infected, and a simple change of air was by no manner of means sufficient, as has already been shown. In addition, these observations throw considerable light on the means by which contagious diseases are spread, for often a room, a house, or the entire neighborhood appears to be infected. It must also be remembered how, in times of plague, large fires were resorted as to a method of purifying the air.
With the infinite distribution of germs, and as they are always present in all places where any organic portions of vegetable or animal matter are undergoing decomposition, it becomes, under certain circumstances, exceedingly difficult, and at times even impossible, to trace the direct effect of these minute germs. The organism is exposed to the destructive action of the most minute creation; several changes in this case give to them the direct effect of the acting germs. The investigation of the chemist does not extend beyond the chemical changes; nevertheless these phenomena are directly explained by the microscope, without which, in the present case, the discovery of the cause would have remained unknown.—Arch. der Pharm., 214, 158.
* * * * *
If two drops of phenic acid are diluted with three thousand to five thousand parts of water, a distinct blue color is produced by one drop of solution of perchloride of iron.
The addition of six or eight drops of glycerine entirely removes the color, and if any glycerine was present in the liquid the reaction does not take place at all. By this test the presence of 1 per cent. of glycerine can be detected. It may be applied to the analysis of wines, beers, etc., but when there is much sugar, extractive or coloring matter, the test can only be applied after evaporating, dissolving the residue in alcohol and ether, evaporating again, and then redissolving in water. Alkaline solutions must be first acidulated.—Pharm. Zeit. fuer Russ.