306 KANSAS CITY REVIEW OF SCIENCE. 



Or per pound of refined copper : cents. 



Mining, dressing and transportation . . . . , 5.28 



Smelting and refining 3.28 



Total cost per pound, refined copper 8.56 



Value of refined copper in St. Louis 16.00 



Net profit, per pound, copper 7.44 



The value of refined copper has averaged over 18 cents for the past year or 



so, but 16 cents has been taken as a satisfactory average in the estimate above. 

 The ore taken from these mines runs about 20 per cent copper, according to 



Prof. Potter, and about 18 per cent according to Mr. Nicholson. — Age of Steel. 



A COAL PROBLEM. 



The production of anthracite coal last year reached about 28,500,000 tons. 

 This amount is something above the average, but will, in turn, be surpassed by 

 the output this year. It is estimated that not less than 30,000,000 tons will be 

 mined before next January, and the annual production hereafter, under ordinary 

 circumstances, is not likely to fall below that amount. These figures are more 

 significant than they appear to be at first sight. 



It is not too much to say that the exhaustion of the anthracite coal-fields of 

 this country is in sight. There are deposits in Rhode Island and Virginia, and 

 small quantities elsewhere ; but by far the largest part of the anthracite beds lies 

 in seven counties of Pennsylvania. Four great fields are recognized, their re- 

 spective areas being 159, 92, 194 and 38 square miles — total 483. To this limit- 

 ed tract the United States looks for its anthracite coal. How much was there in 

 it when mining began, scarcely sixty years ago? How much has already been 

 consumed? How long will what remains last? 



The thickness of the beds ranges from thirty to sixty, or perhaps seventy-five 

 feet. But the coal measures are not consecutive or of equal value. Some of 

 them are so thin as to be at this stage valueless. Faults are numerous. The 

 gigantic crushing powers which nature exerted while the coal was forming squeez- 

 ed some veins out of existence. Others can be mined only with great difficulty. 

 Taking it for granted that the coal land in all underland with workable seams, 

 and knowing the number of tons per foot thickness per square mile, the original 

 contents of the fields may be calculated. It approximated 9,800,000,000 tons. 

 But it must be remembered, not only that much of this coal is not available, but 

 also that the present methods of mining are very wasteful. Even from the rich- 

 est mines only a small part of the coal is taken. Much of that left behind can 

 never be secured hereafter, no matter how high the price may become. 



A writer in the New York Sun, who has investigated the subject with some 

 care, says that the best engineering science assumes that only one-third of the coal 

 in first-class seams — the deepest and most faultless — only one-fourth of that in 



