proceedings: Washington academy of sciences 297 



ordinary foods meat is the most expensive. Other tables were pre- 

 sented that gave the actual quantities and kinds of food used at cer- 

 tain schools, some of which strikingly confirmed the general belief that 

 one eats more during his "teens" that at any other time of life. 



The 109th meeting of the Academy was held in the Auditorium of 

 the New National Museum, Friday afternoon, April 21, 1916, with 

 President L. 0. Howard in the chair and an appreciative audience 

 present. Dr. E. B. Forbes, Chief of the Department of Nutrition of 

 the Ohio Agricultural Experiment Station, gave an illustrated lecture 

 on Investigations in the mineral metabolism of animals. 



Careful investigations, especially with cattle and hogs, have shown the 

 importance of having sufficient amounts of certain mineral substances 

 in their food. Of these calcium in some assimilable form is needed in 

 greatest abundance, particularly during the period of rapid growth. 

 Hence blue grass, which is rich in calcium salts, is an excellent food for 

 growing stock, while an all-grain food, poor in such substances, is inade- 

 quate. Among the interesting developments of the work was the fact 

 that good milch cows secrete more mineral matter during the period of 

 full lactation than they assimilate from even the best food, and thereby 

 suffer a kind of mineral exhaustion. 



The 110th meeting of the Academy was held jointly with the Geo- 

 logical Society of Washington in the lecture room of the Cosmos Club, 

 Wednesday evening, April 26, 1916, with Dr. A. C. Spencer presiding 

 and about 60 persons present. 



Dr. K. F. Kellerman spoke of Bacteria as agents in the precipita- 

 tion of calcium carbonate. Illustrations were shown of spherulites formed 

 through bacterial agency from solutions of calcium sulphate, calcium 

 acetate, and artificial sea water, which are practically indistinguishable 

 from those formed in nature. 



Dr. J. Johnston discussed Some factors which influence the deposi- 

 tion of calcium carbonate. The fundamental importance of the solu- 

 bility-product in relation to saturation was explained, and the different 

 methods of producing precipitation or inducing solution discussed. 

 The greater solubility of calcium carbonate in cold water obviously 

 must lead to its depletion in the higher latitudes and its accumulation 

 in equatorial regions, a process which appears to be in full operation. 



Dr. H. E. Merwin described The forms of calcium carbonate and their 

 occurrence. There are at least three easily distinguishable crystallized 

 forms of calcium carbonate and a number of doubtful forms. The 

 form deposited from a solution depends very largely upon tempera- 

 ture, though there may also be other contributing causes. 



In the discussion that followed Dr. T. Wayland Vaughan spoke of 

 the oolitic deposits of Florida and their problems, and Dr. Chas. D. 

 Walcott described the similar silicious deposits of the Yellowstone 

 Park. 



