858 



POPULAR SCIENCE MONTHLY. 



place of the dead — consist of menhirs from 

 two feet to twenty feet high, are sepulchral, 

 and are evidently the work of the same race 

 that built Avebury and Stonehenge, though 

 data as to the time are wanting. Stonehenge 

 is obviously the latest of the three, for the 

 stones there are hewn out and fashioned with 

 mortise blocks, etc., while Avebury and Car- 

 nac are rough and unhewn. 



Coal-Mine Acids in the Scbnyllcill River. 



— It is shown in a paper by Prof. 0. C. S. 

 Carter that the Schuylkill River, above the 

 city of Reading, is so strongly charged with 

 sulphuric acid and sulphate of iron that it 

 can not be used as a water supply, or, on ac- 

 count of its corroding boilers, for the gen- 

 eration of steam, and is very detrimental to 

 fish, so that there are practically none in the 

 river between Reading and Tamaqua. The 

 acidity of the river is due to imjiurities found 

 in coal. Before coal was mined in Pennsyl- 

 vania the river, it is said, was free from 

 acidity from its mouth to its source, and fish 

 were found along its entire course. It is 

 also said that the amount of acid in the Big 

 Schuylkill from Pottsville and beyond has 

 been decreasing since 1868, owing to the 

 transfer of mining operations to the other 

 side of the mountains, where the streams 

 drain into the Susquehanna, and that the 

 amount of sulphuric acid in the Big Schuyl- 

 kill in 1885 was only one half of what it had 

 formerly been. These statements can not be 

 strictly verified for want of means of making 

 comparative analyses, but are taken as true. 

 Thanks to the decrease of acid, a few hardy 

 catfish have found their way up to the region 

 between Port Clinton and Pottsville, but no 

 other fish ; but even the catfish are not found 

 in the river lower down, between Port Clin- 

 ton and Reading, because of the discharge of 

 acid waters by the Little Schuylkill at Port 

 Clinton. The water loses its acid character 

 in the vicinity of Reading, and neutralization 

 is complete a short distance below. This is 

 brought about by the pouring in of the hard, 

 limestone waters of Maiden and Tulpehocken 

 Creeks near Reading. At the mouths of these 

 streams the sulphate of lime is precipitated 

 by their action, rendering the water almost 

 milky in appearance. In 1882, when a num. 

 ber of abandoned coal mines were opened 

 and the excess of acid water was pumped 



into the river, there was more of it than the 

 limestone streams could neutralize in the dry 

 season ; it passed far below the city of Read- 

 ing, and hundreds of dead fish were observed 

 floating in the river. 



An Endless Source of Carbonic Acid. — 



Prof. E. W. Claypole's president's address at 

 the last meeting of the American Microscopi- 

 cal Society — Microscopical Light in Geological 

 Darkness — concerns the aid furnished by the 

 microscope in geological study. Among the 

 revelations afforded by means of this instru- 

 ment is that which it has yielded, in the hands 

 of Mr. H. C. Sorby, of Sheffield, England, of 

 the existence of innumerable inclusions of 

 liquid carbonic acid in the rocks. As investi- 

 gation has gone on, the abundance of these 

 bubbles has been more and more realized, and 

 they are now found to be present " by myriads 

 and by millions, and not in gems only, but in 

 other crystalline minerals. In size they range 

 between the one-thousandth and the fifty- 

 thousandth of an inch, but they are so mul- 

 titudinous as often to impart a white tint to 

 the crystal, and many specimens of milky 

 quartz owe their whiteness solely to the pres- 

 ence of these innumerable bubbles. In some 

 of the Cornish granites the cavities make 

 five per cent of the volume, and yield four 

 pounds of the liquid to every ton of the 

 rock." Mr. J. C. Ward is quoted as saying 

 that more than a thousand millions of them 

 might be contained easily within a cubic inch 

 of quartz. The fact is used to cast light on 

 the problem of the origin of the coal. Coal 

 is derived from plants, which have extracted 

 carbon from the carbonic acid of the atmos- 

 phere. Whence was that carbonic acid de- 

 rived ? It has been said that it was one of 

 the original constituents of the atmosphere. 

 But Professor Claypole adduces many reasons 

 to show that all the carbonic acid represented 

 in the coal beds could never have been in the 

 atmosphere at one time. How, then, and 

 whence, were the successive supplies intro- 

 duced ? Besides Mr. Sorby's experiments, 

 those of Professor Tilden and others show 

 that rocks of various kinds and in various lo- 

 calities yield gases, of which hydrogen and 

 carbonic acid are the most abundant, in pro- 

 portions ranging from 1.3 to 17.8 of the bulk 

 of the rock, whence it may be inferred that 

 these gases are occluded in most rocks. Now^ 



