260 



KNOWLEDGE. 



[November, 1901. 



The site of the cities of the plain has been placed 

 by some in the northern, and by others in the southeni 

 part of the lake. Among the legends which were once 

 commonly believed, was that the vestiges of Sodom and 

 Gomorrah could be discerned centuries afterwards. Thus 

 Josephus writes: — " The traces of the live cities are still 

 to be seen, as well as the ashes growing in their fruits, 

 which fruits have a colour as if they were fit to be 

 eaten ; but if you pluck them with your hands they 

 dissolve into smoke and ashes.'' 



The marshes adjoining the sea arc very unhealthy, 

 and malaria and fever arc prevalent among the few 

 tribes which dwell near them. Several explorers have 

 lost their lives from the results of exposure and fever. 



The water in mass is bluish-green and resembles seiu- 

 water. All accounts from Strabo to the present day 

 agree as to its great density. Pocockc, who bathed in 

 it in 1743, found he could lie upon the surface withoiit 

 sinking. This characteristic has been so exaggei'ated by 

 the earlier traveller that legends have attributed 

 miraculous properties to the water. For instance. Sir 

 John Maundeville in his Travels, published between 

 1357 and 1371, wrote: — "And neither Man, Beast, nor 

 anything that beai'eth Life in him may die in that Sea. 

 And that hath been proved many times by Men that 

 have deserved to be dead, that have been cast therein 

 and left there 3 Days or 4, and they might never die 

 therein ; for it receiveth no Thing within him that 

 beareth Life. And no man may drink of the water for 

 Bitterness. And if a Man cast Iron thereon it will float 

 above. And if Men cast a Feather therein it will sink 

 to the Bottom, and these be Things against Nature." 



The first recorded analysis of the water was made in 

 1778 by Lavoisier by the then imperfect methods of 

 analysis. He found it to contain 46.6 per cent, of solid 

 matter, consisting of 40 per cent., of calcium and 

 magnesium chlorides, and the remainder of common salt. 

 Ana.lyses have since then been made by Marcot in 1807, 

 . by Gay Lussac in 1818, and by T. and W. Herapath 

 in 1850. 



A specimen of the water, which I have recently 

 analysed, was brought home some yeai's ago by Mr. 

 Boyle, a descendant of Robert Boyle s brother. It was 

 given to me by his daughter, Mrs. Keely, to whom I 

 take the opportunity of expressing my best thanks. 



It was a yellowish dirty-looking liquid with an ex- 

 tremely saline taste. Its specific gravity compared with 

 distilled water at 60° F. was 1.203, a result which agrees 

 wpU with the figures obtained by Marcet (1.211) and 

 by Lavoisier (1.2403). The variations being satisfac- 

 torily accounted for by the difl'erent period and 

 distances from the mouth of the Jordan at which the 

 samples were taken. 



It is thus one of the densest natural waters known, 

 its specific giavity far exceeding that of sea water, which 

 only averages 1.027. 



Wo may express these figures in other terms by saying 

 that a gallon of distilled water weighs 10 lbs., a gallon 

 of ordinary sea^wat€r 10;^ lbs., and the same volume of 

 Dead Sea water 12 lbs. 



This accounts for the remarkable buoyant properties 

 of the water, though obviously neither iron nor even 

 aluminium with a specific gravity of only 2.6 would 

 float upon it. 



The great density of the water is due to the large 

 quantity of saline matter in solution. The amount 

 found by Lavoisier was doubtless considerably too high, 

 for his analysis was made by the method of crystalliza- 

 tion ; and the results obtained by other chemists are 



in better agreement with the 24.46 per cent, which I 

 have found. 



The accumulation of salt must be attributed to the 

 ceaseless evaporation of water and continual intro- 

 duction of fresh supplies charged with salts from the 

 surrounding strata. In sea-water the total salts only 

 average 3.5 per cent. 



This excess of saline matter has a very unpleasant 

 cff'ect upon bathers, and, according to Legh, produces 

 a sort of temporary blindness. On leaving the water 

 the skin is rapidly covered with a thin crust of salts. 



On igniting the residue left on evaporating the water 

 it darkened, owing to the combustion of the organic 

 matter. This was present in considerable quantity 

 (about 0.5 per cent.), and jirobably^ consisted of 

 bituminous substances derived from the asphalt. 



The chlorine amounted to 15.9 per cent., and in the 

 residue was chiefly present in combination with mag- 

 nesium, calcium, and sodium. The chief constituent of 

 the water was thus magnesium chloride, which formed 

 9.06 per cent, of the total solid matter. In sea-water 

 this salt is present to the extent of about 3.7 parts 

 per thousand. 



By combining the amount of sodium (3.35 per cent.) 

 with its equivalent quantity of the chlorine, the amount 

 of common salt in the water was calculated to be 8.52 

 per cent. It is thus much more than is present in sea- 

 water, where it averages about 2.8 parts per cent. It 

 is interesting to note, however, that whereas in sea- 

 water the amount of ordinary salt is seven times that 

 of the magnesivim chloride, in the Dead Sea water they 

 are present in approximately equal proportion. The 

 calcium, which amounted to 1.3 per cent., was probably 

 originally in combination with part of the chlorine, with 

 the exception of a small quantity combined with the 

 sulphuric acid as calcium sulphate or gypsum. 



Bromine probably as magnesium bromide composed 

 0.24 per cent, of the water, and potassium as potassium 

 chloride 1.20 per cent. Small quantities of iron, 

 aluminium, and silica were also identified. 



The calculated composition of the solid constituents 

 of the water, excluding the organic matter, was as 

 follows:— Percent. 



Magnesium Chloride ... ... 9.06 



Calcium Chloride ... ... ... 3.49 



Sodium Chloride 8.52 



Potassium Chloride 2.37 



Iron and Aluminium Chlorides ... 0.55 



Calcium Sulphate ... 0.148 



Ammonium Chloride 0.029 



Silica — ... 0.083 



Magnesium Bromide ... ... 0.21 



Total 



24.460 



'm:,^ 



"^i 



Condueted by M. I.Cross. 



'I'm; Mi( u<i.scoi'ic.\L Ex.v.mi.natki.n uy Meiwls. — It is a 

 little singular that a study which has assumed such great 

 importance as the examination of steel and iron under the 



