226 ANNUAL KECORD OF SCIENCE AND INDUSTRY. 



have been preserved in the School of Mines. The depth to 

 which the bore was extended was 210 meters, of which tlie 

 first thirty-five were porphyritic stone, and the latter 175 a 

 red-colored sandstone and conglomerate, and not a trace of 

 coal was found, or is to be expected. Observations of the 

 temperature at various depths seem not to have been under- 

 taken. bth Ber. Nat.Gesells.^ Chemnitz^ 1875, 244. 



COAL-FIELDS OF SPAIN. 



In a paper lately read before the French Society of Engi- 

 neers, the area of the coal-fields of Spain was estimated to 

 equal 150,000 hectares (the hectare equals 1.47 acres). From 

 these deposits only about 500,000 to 600,000 tons of mineral 

 are annually produced, while in Belgium, with the same area, 

 the production is 10,000,000 tons. The Spanish coal-fields 

 are in the provinces of Castile, Leon, and the Asturias. The 

 process of extraction is described as being quite rude and 

 imperfect. 17 Z>, XX., 56. 



SECTIONS OF COAL. 



Dr. C. Johnson gives the following as the method adopted 

 by him in preparing sections of coal: 1. Macerate suitable pieces 

 one quarter or one half inch thick in liquor potassse until they 

 swell or soften. 2. Soak for a few hours in pure water, and 

 drain. 3. Macerate in nitric acid until the color changes 

 from black to brown. 4. Soak for a few hours in water, and 

 drain. 5. Put in alcohol for a few days. 6. Fasten in a cut- 

 ter with paraflin, and make sections, the sections to be 

 mounted in balsam after successive immersions in absolute 

 alcohol and oil of cloves. Medical News, Ci?ici7inati, July, 

 1875. 



COMPOSITION OF CORAL. 



The composition of coral has been carefully investigated 

 by Professor Dana. Ordinary corals have a hardness a little 

 above that of common limestone or marble, giving out a 

 ringing sound when struck with a hammer. This may be 

 owing, he considers, to the carbonate of lime being in the 

 state of aragonite. It is a common mistake to suppose that 

 coral, when first taken from its watery bed, is soft, and hard- 

 ens through exposure. The live coral may feel somewlint 



