23-i ANNUAL OF SCIENTIFIC DISCOVERY. 



the ordinary analytical processes. A part of these results has been published 

 in the proceedings of ihe Boston Society of Natural History, while some of the 

 more important conclusions have not yet appeared. The present article is 

 intended to illustrate the method resorted to in a particular case,' and to give 

 the composition of the matter which forms by the evaporation of sea water, in 

 presence of a large volume of the water, and excluded from matters in suspen- 

 sion, in its relation to the new facts. Analysis had shown that the water of the 

 Carribean Sea, at different depths and in different months of the year (which, 

 from the currents and great evaporation, may be considered as representing 

 the main composition of sea water), contained organic salts of lime, one of 

 which, the crenate, was easily recognised, while one less easily determined 

 awaits further examination. This fact, established by analyses of many 

 samples, suggested the importance of a re-examination of the deposit which 

 falls from concentrated sea water affected by heat, although the deposit in 

 the water of sea-going steamers had been analysed by skilful chemists before. 



A moment's consideration of the circumstances shows that the supply 

 pump of the boilers of a sea-going steamer must take up an average of the 

 superficial waters through which the vessel passes and re-passes, and any 

 deposition taking place in the water of the boilers would represent an average 

 composition in the earthy salts susceptible of deposition. The fine steamers 

 of the Collins line to Liverpool from the port of New York, are provided with 

 boilers composed in large part of vertical tubes, formed of fine brass, drawn from 

 ingots. The water of the ocean is pumped into horizontal reservoirs, from 

 which it rises only so rapidly as the evaporation demands, and hence any 

 deposition taking place in the brass tubes will be free from suspended 

 impurities, and represent such compounds, whether pre-existing in the water, 

 or formed in it by hea"t as it becomes concentrated, while abundance of water, 

 is present. A quantity of this deposition obtained from the polished tubes of 

 brass, when subjected to analysis, gave about twelve per cent, of sub-carbonate 

 of magnesia, to about eighty-three of sulphate of lime, besides phosphate of 

 lime and other products. 



The sub-carbonate of magnesia results from the action of the organic salts 

 of brine on magnesian salts contained in sea water, as takes place in the 

 analysis of sea water, and hence this decomposition, which had been referred 

 to the presence of bicarbonate of lime, becomes a simple case of double 

 decomposition. Experiments show that bicarbonate of lime does not decom- 

 pose magnesian salts, but dissolves with them; while carbonate of lime, 

 boiled with magnesian salts, decomposes them : the action is never perfect in 

 presence of sulphate of lime. A portion of carbon derived from one of the 

 organic acids by the action of heat, is always present, as is also a silicate of 

 iron, which had been dissolved in the water. 



The phosphate of lime found is not bone phosphate existing in the water, 

 but the phosphate containing two proportions of base to one of acid, as found 

 by Dr. Hayes to result in all cases of decomposition of bones in water, 

 either pure or saline. The action of this organic salt, proved to exist in sea 

 water in cementing rocks, is a subject to be considered by itsel 



