644 TRANSACTIONS QF THE AMERICAN INSTITUTE. 



gelatine, &c.; in others they were placed in vessels of wood or 

 unglazed porcelain. He also had recourse to the Osmose process. 

 Thus he succeeded in obtaining chrystals of sulphate of baryta, 

 carbonate of lead, sulphate of strontia, carbonate of bar}i;a, borate 

 of barj'ta, chromate of baryta, oxalate of lime, magnesia, and sev- 

 eral sulphides. He did not, however, succeed in obtaining pure 

 quartz by the reaction of alkaline silicates on certain acids. 



Spectral Lines. 

 Prof. Hinricks, of Iowa State University, communicates to The 

 American Journal of Science his latest deductions founded on the 

 revelations of the spectroscope. Adopting the determinations of 

 Pliicker and Ditscheiner of the wave-len2:th of a great number of 

 the lines laid down in KirchofF's map of the spectrum, b}' a simple 

 geometrical interpolation, he is enabled to find the wave-length (if 

 any of Kirchoff's lines, with great accuracy. The scale he used 

 made the length of the spectrum from B to G nearly 15 feet; in 

 some instances he used a scale 5 times longer, making the spec- 

 trum 75 feet. The examination of the determinations for 13 of the 

 chemical elements and four compounds, shows that the dark lines 

 of the elements are equidistant throughout the spectrum, but of 

 varying intensity, many not being observed (or observable) at all; 

 and Hinricks further -finds that Ihe intervals between the observa- 

 ble lines ar© expressible as simple multiples of the equal distances 

 indicated by all. 



Steam Power on Canals. 



Steam power has been applied on a canal in Ireland 160 miles 

 long, having only 30 feet of navigable width, and a depth of 5 

 feet 2 inches. Its locks are only 60 feet long, by 13| wide. One 

 steamer, propelled by a screw, drew three boats, each containing 

 40 tons of cargo, at about 2^ miles per hour. On a long level of 

 25^ miles, two steamers performed the work so well that horses 

 have been withdrawn from that portion of the canal. The screw 

 which had been proved to be the best had a width of blade at the 

 circumference of 32 inches cut away at the base to the extent that 

 was consistent with strength ; its pitch was an increasing one, 

 varying from 5 feet 3 inches to 7 feet 9 inches. 



On the Erie canal — navigated by boats, each carrying on the 

 averasre more than five times the load of a boat on the Irish 



