ADDENDA 



FKOM PERIODICALS RECEIVED WHILE THE FOREGOING 

 MATTER WAS IN PRESS. 



Bunsen's filtration process; paj^e 33. R. S. Dale {Chem. News, 

 Eiig., Ed. 20, 108) states, that more rapid filtration can be obtained by 

 substituting platinum-wire gauze, for tlie foil in the funnel, without any 

 more danger of tearing tlie paper; and tlie gauze funnel can be fitted in 

 the glass one with sufficient accuracy, by means of a cone of wood turn- 

 ed to the proper angle. Undoubtedly, tliis gauze fuimel can be advan- 

 tageously used in cases where the pressure on the liquid in the filter is 

 much less than an atmosphere, as when the rarefaction of the air in the 

 filtering flaslc is effected by means of the flow of water from one bottle 

 to another. 



Standard acid and alkaline solutions ; page 48. Dr. Fleisclier 

 {Chem. News ; Am. Repr., 5, 8!^) gives some good reasons for preferring 

 a standard hydrochloric acid, instead of sulphuric; it forms soluble 

 salts with all the alkaline earths, is readily obtained pui-e, is estimable 

 with great accuracy by a standard solution of argentic nitrate as well as 

 by an alkali, and its constancy is unimpeachable. The standard of the 

 acid can be determined by means of a weighed amount of pure calcic 

 carbonate, that has been slightly heated, or by the standard argentic so- 

 lution. 



For a standard alkaline solution, ammonia has many advantages over 

 soda; it is more easily obtained pure, and has so slight a tendency to 

 absorb carbonic acid from the air, that no special provision need be made 

 against it. 



As some neutral amnionic salts have a slight acid reaction when the 

 solution is hot, the liquid to be tested should be cold. A solution con- 

 taining half an equivalent of ammonia in the litre, is recommended. 



Both of these standard solutions should be kept in a cool place, free 

 from dust. If the ammonic solution is exposed to hot summer weather, 

 the bottle containing it should be placed in cold water that is renewed 

 every day; by exposure to a temperature above 25° C, the standard of 

 the solution Avill be very slightly altered. 



Estimation of iron by the permanganate process ; page 07. M. 

 Moyaux {Revue Universelle cles Mines, etc., Chem. News, Am. Repr., 5, 179) 

 states, that the useof ammonio-ferrous sulphate to determine the staud- 

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