126 



CHEMISTRY. 



ficial heating. Variations in the degree of cold 

 between one night and another account for 

 corresponding differences in the gravity of the 

 poisoning effects produced. Gas filtered through 

 the soil from the mains may be quite odorless 

 nntil it has collected in large amount, and 

 herein lies the danger to dwellers in the base- 

 ment. The remedy, when symptoms (head- 

 ache) of gas-poisoning occur, is to open the 

 windows. 



Atomic Weights. Thomas Hilditch has called 

 attention to possible sources of error in the 

 determination of the atomic weight of oxygen, 

 arising from the fact that the hydrogen used 

 in the experiments has been obtained by the 

 solution of impure zinc in sulphuric acid, and 

 is liable therefore to contain foreign admixt- 

 ures. Among the substances with which it 

 may be infected are hydrides of carbon, sul- 

 phur, antimony, and arsenic, sulphur dioxide, 

 carbon dioxide, oxides of nitrogen, free oxygen, 

 nitrogen, and water. He suggests that, in fu- 

 ture determinations of oxygen, the hydrogen 

 should be derived from the electrolysis of water. 



From the closely coordinate results of seven 

 experiments with cerium chloride and silver 

 nitrate, H. Eobinson has determined the atomic 

 weight of cerium at 140-2593, silver being 107'- 

 93. 



A few years ago Nilson and Petterssen, con- 

 cluded from their experiments on the specific 

 heat of glucinum, or beryllium, that the atomic 

 weight of that element is 13-65, and not 9-1, 

 as had generally been assumed. This was chal- 

 lenged, and Nilson reexamined the question, 

 and claimed to have confirmed their former 

 result. Kecently, however, they have gone into 

 the subject again, and now announce that their 

 former conclusion was wrong, and that the old 

 figure of 9*1 is correct. 



Prof.Cleve has described methods for extract- 

 ing and purifying the earth samaria. From 

 determinations of the amount of sulphate ob- 

 tained from quantities of this oxide, he calcu- 

 lates the atomic weight of the metal samari- 

 um as 150. Various salts of samarium are 

 described. The metal is closely allied to di- 

 dymium. 



Bougartz has made a series of new determi- 

 nations of the atomic weight of antimony by a 

 method proposed by Classen, which consists 

 in oxidizing by means of hydrogen peroxide 

 the hydrogen sulphide set free fromantimonious 

 sulphide by hydrogen chloride. The results of 

 twelve experiments gave a mean of 120-193 ; a 

 number which confirms the values heretofore 

 obtained by Schneider and by Cooke. 



Friedel, having obtained some exceptionally 

 pure and white specimens of diamond, very free 

 from ash, has submitted them to combustion 

 in a current of oxygen, by aid of a carefully ad- 

 justed apparatus, with a view of determining 

 the atomic weight of carbon. In the first of 

 two combustions, 0-4705 gramme of clear white 

 Cape diamonds gave 1*7208 gramme of carbon 

 dioxide. Since the ash weighed 0-0007 gramme, 



the carbon consumed weighed 0*4698 gramme, 

 and a loss of 0-0021 gramme carbon was shown. 

 Considering that of oxygen as 16, this experi- 

 ment gives 12*017 as the atomic weight of car- 

 bon. In a second determination 12*007 was the 

 figure obtained. 



The following recent redetermmations of 

 atomic weights have been published: By 

 Thorpe, titanium = 48; by Baubigny, niobium 

 = 58'75 ; by same, copper = 63*46 ; by Brauner, 

 tellurium = 125 ; by Lowe, bismuth = 207*33 ; 

 and by Marignac, bismuth = 208*16 ; manga- 

 nese = 55*07; zinc = 65*27, magnesium = 24*37. 



Analytic Chemistry. Prof. Dittmar has pub- 

 lished a report on the composition of ocean- 

 water as determined by the analyses of speci- 

 mens collected during the Challenger Expedi- 

 tion from various parts of the oceans and from 

 different depths. It embodies the results of 

 seventy-seven complete analyses that were made. 

 Leaving out of view those of the thirty elements 

 known to exist in sea-water which are present 

 only in too minute quantity to be determined 

 in small samples, attention was given to the 

 accurate estimation of the chlorine, sulphuric 

 acid, soda, potash, lime, and magnesia. The 

 principle previously declared by Forchhammer, 

 that the percentage composition of the salts of 

 sea-water is the same in all parts of the ocean, 

 was confirmed, and was extended to all depths 

 except in the case of lime, the proportion of 

 which increases with the depth. The determi- 

 nation of the amount of carbonic acid was at- 

 tended with difficulties, but the observations 

 gave the three results that 1. Free carbonic 

 acid in sea-water is the exception; as a rule 

 the carbonic acid is less than the proportion 

 corresponding to bicarbonate. 2. In surface 

 waters the proportion of carbonic acid in- 

 creases when the temperature falls, and vice 

 versa. 3. Within equal ranges of temperature 

 it seems to be lower in the surface water of the 

 Pacific than it is in the surface water of the 

 Atlantic Ocean. 



In regard to alkalinity, the analyses show 

 that in sea-water salts there is a distinct pre- 

 ponderance of base over fixed acid. The alka- 

 linity of bottom waters was found to be dis- 

 tinctly greater than that of those from the 

 surface, and this increase was exactly propor- 

 tional to the larger quantity of lime present in 

 the former. The determination of the amounts 

 of oxygen and nitrogen held in absorption were 

 not wholly satisfactory, and Prof. Dittmar 

 gives his results only tentatively. The amount 

 of air which ought theoretically to be absorbed 

 by sea-water of the temperature and at the 

 pressure at which each sample was collected 

 was first calculated, and then, from the actual 

 amount of nitrogen found, the quantity of oxy- 

 gen which should be associated with it was ar- 

 rived at. The quantities of air found in solu- 

 tion were usually in defect of calculation, as 

 might be expected when it is recollected that 

 the water of the ocean is always in motion, the 

 temperature and pressure to which it is ex- 



