54 



THE GUIDE TO NATURE 



IMuscovite mica is a normal constituent 

 of granite, gneiss, and similar rocks. 

 Deposits from which sheet mica is ob- 

 tained, are found in a coarse granite 

 called pegmatite. Its preparation is sim- 

 ple. When freed from rocks, it is split 

 into blocks by the use of wedges, and 

 then cut into various sizes. 



The picture shows a view of some of 

 the mica mined by the Ridgeway Mica 

 Company, Ridgeway, Virginia. North 

 Carolina furnishes nearly half the mica 

 now used. 



The Ridgeway people take out about 

 15,000 pounds monthly. The largest 

 block removed weighed more than 3,000 

 pounds. The mine apparently contains 

 enough mica to keep the owners busy for 

 nearly a century. 



Mica, especially sheet mica, is often re- 

 ferred to as isinglass. This is an erro- 

 neous application of the word, as mica 

 and isinglass are two entirely different 

 things. 



Isinglass, the dried swimming bladder 

 of certain fishes, is prepared by tearing 

 the air bladder from the back of the fish, 

 washing it in clear water, and removing 

 the outer black skin. It is then spread 

 on a board to dry, and to prevent shrivel- 

 ing, is tacked to the board. The best 

 quality is made from sun-dried sounds. 

 After being thus dried the sound is 

 moistened with warm water and the in- 

 terior glossy skin removed by rubbing. 

 It is then pressed between two highly 

 polished iron rollers. If it is desired to 

 extract the gelatin, which sometimes 

 amounts to more than ninety per cent., 

 the sound is bleached in a sulphuric acid 

 solution. This causes it to swell into a 

 mass, which, when dry, is bright and 

 colorless. 



Pure isinglass should be free from 

 odor and taste. If not tasteless, it is not 

 pure. It is used for the same purposes 

 as gelatin, and in cement. It is the isin- 

 glass in court plaster that makes the 

 plaster adhesive. 



Isinglass is prepared in many coun- 

 tries, but principally in Manila. Canada, 

 Brazil, Russia, West Indies and East In- 

 dies. The best is probably that from the 

 sturgeon, but the bladders of cod and 

 other fish furnish a good quality — From 

 the "Southern Fruit Grower." by per- 

 mission. 



Copper Rocks and Boulders in Sound 

 Beach. 



ArcAdiA has recently received from 

 the mines of the Calumet and Hecla Min- 

 ing Company at Calumet, Michigan, two 

 samples of native copper, one a rock 

 weighing considerably more than a quar- 

 ter of a ton, the other a boulder of forty- 

 eight pounds. The rock has been placed 

 in an appropriate position at the entrance 

 to the Welcome Reception Room and as 

 nearly under the word "Welcome" as is 

 convenient. This seems especially fitting, 

 since both specimens have been presented 

 to The Agassiz Association by Mr. R. L. 

 Agassiz, Vice President of the Calumet 

 and Hecla Mining Company, and grand- 

 son of Louis Agassiz, for whom the sci- 

 entific association is named. The Calu- 

 met and Hecla Mining Company has been 

 so intimately connected with the name of 

 Agassiz, and the name Agassiz is 

 of nature, that a peculiar significance in- 

 heres in this great mass of copper as an 

 emblem of the welcome that we extend 

 to all to share in the benefits of this 

 nature study institution. 



The mineralogical section of ArcAdiA 

 has grown extensively in the past year. 

 The fireplace compose-:! of minerals from 

 all parts of the country, mostly contri- 

 buted by friends of The Agassiz Associa- 

 tion, has acted as a nucleus, around which 

 a large number of interesting specimens 

 has rapidly accumulated. 



The ancient superstition that gun- 

 fire, Fourth of July, and blasting, bring 

 on rain, seems to be pretty well dis- 

 posed of by the weather records of the 

 artillery proving-ground at Shoebury- 

 ness, England. Here are tried out, al- 

 most daily, the largest guns made — 

 yet the locality has almost the smallest 

 rainfall in the United Kingdom. 



A grandson of Charles Darwin, him- 

 self a scientific man of no small parts, 

 has perished in Flanders. 



The Oregon Experiment Station re- 

 ports a flock of fifty hens with an aver- 

 age of 213 eggs apiece during one 

 calendar year ; with 220 for the average 

 of the actual laying year of each parti- 

 cular hen. The world's champion layer, 

 which last year produced 303 in 365 

 days has now brought her score to 505 

 and broken the two-year record. An- 

 other bird claims the astonishing total 

 of 819 eggs in four years. The average 

 farm hen" attains from fifty to seventy- 

 five. 



