INDUSTKIAL PROGRESS DURING THE YEAR 1876. ccxiii 



cities has been attended with considerable success, as appears from 

 the following abstract of a presentation of the subject before the 

 French Academy. This salt possesses, in addition to its eminent 

 deliquescent properties, in virtue of which it absorbs moisture with 

 the greatest avidity, and retains it, the advantage of being excellent- 

 ly adapted for this use by reason of its having little or no commer- 

 cial value, so that in certain localities it is looked upon as a nui- 

 sance. During tlie past few years the principal streets of Rome have 

 been watered with a solution of chloride of calcium, obtained from 

 the numerous pyroligneous acid works in its vicinity. The result is 

 reported to be that the dampness communicated to the road, instead 

 of disappearing in a few hours, as would be the case when water 

 alone was used, remains for a whole week, the road continuing damp 

 without being muddy, and presenting a hard surface, on which nei- 

 ther wind nor passing pedestrians nor horses have any effect. In 

 course of time, also, the road becomes covered with a sort of crust, 

 which increases the durability of the surface. M. Houzeau, in dis- 

 cussing this subject before the Academy, estimated that the use of 

 this solution showed a saving over that of water alone of over thirty 

 per cent. The same savant likewise attributes to this method of 

 watering the streets certain hygienic virtues which deserve consid- 

 eration, to wit : The chloride of calcium obtained from the pyro- 

 ligneous acid works always contains appreciable quantities of tarry 

 matters and perchloride of iron, the dissemination of which in the at- 

 mosphere, it is affirmed, is most salutary; wdiile, finally, the complete 

 suppression of dust, which is attained by this simple but efficacious 

 remedy, must needs exert a most beneficial effect upon public health. 

 Professor E. W. Dory has suggested a new and, it is affirmed, very 

 sensitive test for alcohol, which, if it realize the claims made for it, 

 may prove to be of much practical value. The reagent employed in 

 this case consists of a solution of molybdic acid in strong suliDhuric 

 acid. When brought into contact with this solution, a deep azure- 

 blue coloration is brought out, if alcohol is present. This test is af- 

 firmed to be so sensitive that a quantity of alcohol as minute as the 

 one thousand six hundred and sixty-sixth part of a grain may read- 

 ily be detected. Professor Dory, in commenting upon this reaction, 

 points out the utility of his observation by reference to the frequent 

 substitution of alcohol for chloroform in medical compounds and 

 mixtures, and affirms that such adulteration, which may produce the 

 most injurious effects upon the sick, may be at once detected by 

 this process. Should this reaction be found to be what is claimed 

 for it, it will prove of great value in general laboratory practice. 



ENGINEERING IN GENERAL. 

 One of the noteworthy engineering events of the past year was the 

 successful removal of Hallett's Point Reef, one of the most formida- 



