445 



miles eastward, descends at tlie rate of 9 feet per mile. The Arkansas, 

 from the mouth of the Aplshpa to Fort Atkinson, has a fall of between 

 8 and 9 feet to the mile. The descent of the North Platte, from Fort 

 Fetterman to its junction with the South Platte, is 7 feet, and the South 

 Platte, from Denver to the junction, is between 9 and 10 feet per mile. 

 The fall of Snake River from the mouth of Boss's Fork, north, is about 

 6 feet to the mile. These figures show the practicability of distributing 

 the water of these streams over, the plains for the puri^ose of irrigation. 

 Of mountains, we have six in these tables whose summits rise above 

 14,000 feet. These are: Mount Harvard, 14,270; Pike's Peak, 14,210; 

 Gray's Peak, 14,145; Mount Lincoln, 14,123; Mount Yale, 14,078; 

 Long's Peak, 14,050. These measurements furnish data for conclusions, 

 both curious aud important, connected with the study of climatology 

 and the adaptation of the "Great American Desert" to agriculture, 

 stock-raising, &(i. 



Freservhip action of doracic acid. — It has been found that boracic 

 acid has a preservative action upon milk and beer, and it is stated that 

 one graui added to a quart of milk keeps it sweet and fresh in hot sum- 

 mer W'eather for one hundred and twenty hours, while milk not treated 

 in this way will become sour in thirty-six hours. The addition of bora- 

 cic acid to milk does not injure it for use, but the cream is separated far 

 more slowly. 



Spontaneous comliustion of wood. — A certain French writer gives an 

 account of the spontaneous combustion of a wooden beam in a building 

 at Eibemont, (Aisne.) The beam was exposed to the direct rays of the 

 sun, and during one of the hot days of summer it was found to be on 

 fire, the combustion proceeded slowly but was quite distinct, and emit- 

 ted a smoke which had a curious appearance, and on blowing on the 

 wood it burst into a fiame. It is asserted that the fire was due to the 

 heat of the sun alone. 



Chemical constitution of tannic acid. — The doubtful character of the 

 chemical constitution of tannic acid has led to some very interesting in- 

 vestigations. Doctor Schilf has lately come to the conclusion that it is 

 an alcoholic anhydride of gallic acid, or di-gallic acid. In other words, 

 he considers that it is an ether which bears the same relation to gallic 

 acid as ordinary ether does to alcohol. Since, therefore, gallic acid 

 differs from tannic acid merely in the elements of water, the discovery 

 of some method by which these elements could be displaced might lead 

 to some practical results with regard to the processes of tanning. 



The value ofgirondin as a disinfectant. — The prevalence of disease in 

 many of our large cities, due in a great measure to the filthy condition 

 of the streets, shows the necessity of having some effectual disinfectant. 

 To this end the board of health in New York City has made a series of 

 experiments upon the value of all the disinfectants in the market, and 

 decided that girondin, a French invention, is the most effectual. It is 

 due to the use of this article, as is claimed, that the city has been kept 

 free from epidemic during the past two years. 



Test for sill: goods. — If a sample of silk goods suspected to contain 

 other kinds of fiber be treated with hydrochloric acid of 1.13 specific 

 gravity the silk will be dissolved, while other kinds of fiber, such as jute 

 and linen, will remain undissolved. 



Preservation of wood. — F. Sieburger states that the inconveniences of 

 the application of chloride of zinc and so-called water-glass solution, for 



