41 



By a proportional analysis it was found to contain, per cent. 



Phosphate of Lime, .... 92.405 



Chloride of Calcium, 0.540 



Fluoride of Calcium, .... 7.012 



Per Oxide of Iron, 0.040 



Oxide of Manganese, .... 0.003 



100.000 

 It is obvious that Mineral Phosphate of Lime like this is more 

 valuable for agricultural use and for the preparation of Phospho- 

 rus and Phosphates of the Alkalies than burned bones, which 

 contain basic phosphate of lime mixed with a small proportion of 

 Carbonate of Lime ; for the mineral phosphate requires less 

 sulphuric acid in the disengagement of a given amount of Phos- 

 phoric acid. 



Mr. Desor made some statements in relation to the exist- 

 ence of Dunes on the shores of the upper American Lakes. 



They were peculiarly interesting as being the only ones of 

 any consequence, so far as his knowledge went, which had 

 been noticed on the borders of an inland sheet of water. On 

 the eastern shore of Lake Michigan they are several hundred 

 feet high. On the north shore, at Point aux Chiens, they are 

 from eighty to one hundred feet high, the highest being half a 

 mile from the Point. They gradually diminish in S'ize, extend- 

 ing along the shore to the west some six miles, until they are 

 reduced to heaps not more than twenty-five feet high. They 

 present no signs of stratification, nor do they contain pebbles, 

 except a few in the depressions between the hillocks where they 

 have been thrown by the waves in severe gales. The back 

 slope has an angle of 32°. In those positions where the ridges 

 are perpendicular to the coast line, the steep side is always oppo- 

 site to that of the prevailing wind. This feature is also notice- 

 able at several places along the shore of Lake Superior. A 

 peculiarity of the dunes of Lake Michigan is, that they are often 

 covered with trees of considerable size. A white pine growing 

 on the top of the highest ridge was found by Mr. Desor to be 

 eight feet in circumference, showing that at this spot the dune 

 has remained unchanged for a considerable time. Dunes, also, 

 occur at White Fish Point, on Lake Superior, at Keewenaw 



