HISTORICAL REVIEW 751 



bonate proved to be the most effective precipitating agents, and these 

 may, and often do, occur in sea-water and in other places where oolites 

 are now forming. They result from the decay or decomposition of ani- 

 mal and plant tissue, and they are most common in warm climates, where 

 life is abundant and decay rapid.^^ 

 He summarizes his results as follows: 



1. The maximum solubility of CaCOg in. sea-water is .0191. 



2. If the limit of solubility of calcium carbonate in the sea-water is 

 exceeded, the C'aCOp will separate out, forming calcite in temperate cli- 

 mates, and aragonite in tropical climates if the temperature of the water 

 is high ; but spherical oolites are never formed by this process. 



3. If the calcium sulphate of the sea-water is precipitated by sodium 

 or ammonium carbonate it will come down as calcium carbonate in the 

 form of aragonite in either warm or cold climates, and for the greater 

 part in the form of spherical oolites. 



4. From a solution of calcium bicarbonate free from other salts the 

 calcium carbonate is precipitated in temperate climates as calcite; in 

 tropical climates, if the temperature is favorable, mostly as aragonite. 



5. From a solution of calcium sulphate free from other salts, the cal- 

 cium will be precipitated by sodium or ammonium carbonate in the form 

 of calcite under either warm (40° C.) or cold (18° C.) conditions. 



6. This demonstrates that the solubility of aragonite is greater in a 

 solution with little or no other salt than in a solution well supplied with 

 other salts, and that it is greater in a cold than in a warm solution. 

 Calcite is exactly the reverse. Consequently at the same temperature 

 sea-water will dissolve more calcium carbonate than fresh water; but 

 there are circumstances under which aragonite and calcite are soluble to 

 the same degree, and consequently they can form at the same time. 



7. Calcium carbonate and calcium sulphate are more easily soluble in 

 sea-water than in pure water. 



Linck concluded as a result of his investigations that the aragonite 

 oolites now forming in the sea are the result of chemical reaction between 

 the calcium sulphate of the sea-water and the sodium carbonate and am- 

 monium carbonate generated by the decay of animal and plant tissue. 

 Their formation in the warmer regions is not so much due to the greater 

 abundance of organisms in those regions as to the more rapid decay of 

 organic tissue under the warmer climatic conditions. 



He considers the Carlsbad sprudelstein to be formed in the same way 

 as the recent marine oolites and to differ in origin from these only in 



" J. Walther previously suggested that oolites were formed by the decay of organic 

 tissue. Abh. sachs. Ges. Wissensch., Bd. 14 and 16, 1888, 1891. 



