470 CALCIFICATION, CONCRETIONS, AND INCRUSTATIONS 



McCrae^^ has analyzed the lungs of six gold mine workers, in South 

 Africa, finding from 9 to 21.7 grams of ash per lung, of which 29 to 

 48 per cent, was silica; aluminum was also high, and an increased 

 PoOs content was ascribed to the accompanying fibrosis. Klotz^° 

 found from 1.2 to 5.3 grams of free carbon in each lung, of dwellers 

 of Pittsburg, as contrasted with 0.145 and 0.405 grams found in the 

 lungs of residents of Ann Arbor. Hirsch^^ analyzed four average 

 Chicago lungs, finding in grams per lung: 



I II III IV 



Carbon 2.72 0.71 1.20 0.19 



Silica 0.18 0.28 0.69 0.04 



Calcium Oxide 0.45 0.12 0.02 0.05 



^5 "The Ash of Silicotic Lungs," John McCrae, Johannesburg, 1914. 



^0 Aineh Jour. Publ. Health, 1914 (4), 887. General review on anthracosis. 



" Jour. Amer. Med. Assoc, 1916 (66), 950 



