Chemistry and Physios. 481 



form hydrogen-potassium sulphate. Moreover, as the solution 

 becomes more dilute the quantity of this acid salt diminishes 

 until ultimately it is completely converted into the normal salt. 

 The molecular resistance of the hydrogen-potassium sulphate, 

 which varies according to the same law as that of other salts, is 

 proportional to a factor 1+Km«; the proportion of this acid salt 

 in the solution being given by the expression y=Yml The 

 somewhat high value of m* in the formula for the molecular resist- 

 ance, indicates the dissociation of the acid salt. If the molecule 

 of hydrogen-potassium sulphate constitute a single electrolytic 

 molecule, it's resistance at the limit will be that of the normal 

 salt, and in solutions containing not more than one-tenth of a gram- 

 equivalent per liter the difference between the resistances of the 

 two salts will be a vanishing quantity compared with the much 

 greater conductivity of the free acid. It is found that the pro- 

 portion of the acid sulphate, calculated from the observed resist- 

 ances of the liquid, increases with the temperature. Hence, com- 

 bining this with the previous result, it follows that hydrogen- 

 potassium sulphate is more stable in warm and concentrated 

 solutions. At the same temperature and with the same degree 

 of concentration, the proportion of the acid salt increases with an 

 increase in the relative proportions of either the free acid or the 

 normal salt, an excess of the normal salt being more favorable to 

 this change than an excess of sulphuric acid. These results agree 

 with the results of Berthelot's thermo-chemical investigations. 

 Possibly the great variations in the resistance of abnormal salts 

 and of free acids may be due to a progressive dissociation of 

 complex electrolytic molecules, according to the same law as that 

 of hydrogen-potassium sulphate; but this effect, while added to, 

 will not modify the law of the variation of the resistance of salts 

 which are normal in all degrees of dilution. — G. R., civ, 1789, 

 1839; J. Chem. Soc, lii, 882, October, 1887. G. p. b. 



2. On the Detection of minute traces of Carbon dioxide. — In 

 order to detect minute traces of carbon dioxide Rossler has 

 modified the ordinary method as follows: The lower end of a test 

 tube is drawn out to a narrow tube which is then turned upward 

 and to one side, the opening being about a centimeter above the 

 bend. A piece of thin glass tube, rather larger in diameter than 

 the test tube, is drawn out to a gradual taper so that while at top 

 it rests upon the test tube, its lower and capillary end is from l - 5 

 to 2 cm from the bottom of the this tube. The substance to be exam- 

 ined is placed in the bend of the test tube. The capillary funnel 

 is then partly filled with baryta water so as to leave a drop hang- 

 ing from the lower end, and is placed in the test tube. Upon 

 dipping the apparatus in hydrogen chloride, the acid enters the 

 capillary opening of the test tube and comes in contact with the 

 substance in the bend. The evolved carbon dioxide comes in con- 

 tact with the baryta water and produces the well known tur- 

 bidity. To test the delicacy of the apparatus, sodium carbonate 

 was mixed with sodium chloride and inti-oduced into it. When 

 the former was 0'005 gram the turbidity was strong. With 0005, 



