Dr. Kane on the Basic Sulphate of Mercury. SS 



the extra-current in * acts namely as an increase of resistance 

 to the passage of the current, and causes a greater part of it 

 to flow off through I and III or II and III. A voltameter 

 inserted at u, or between I and III or II and III, is, as re- 

 gards the quantity of gas obtained, in exact proportion to the 

 intensity of the spark. The galvanometer gives a similar di- 

 rection for p, p — A, p — A + E and E. All the results ob- 

 tained apply as well for primary currents whose direction re- 

 mains the same, and for those whose direction alternates. 



As bundles of iron wires, when electro-magnetized by means 

 of galvanic, thermic, or frictional electricity, surpass massive 

 bars of the same metal in their physiological effects, and as 

 this phaenomenon may be explained by electric currents which 

 are simultaneously excited in the iron during magnetization, 

 it was interesting to examine how bundles of wires would be in 

 comparison to bars when both were magnetized by bringing 

 them in proximity to a steel magnet. This can be effected by 

 means of a Saxton's machine with wooden anchor, in whose rolls 

 of wire which are connected crosswise, a bundle of iron wires 

 and an iron cylinder act against each other. The experiment 

 shows, that for no action does the current excited by the bundle 

 exceed that from the cylinder : moreover, two similar bundles 

 of wire, one of which was contained in a perfect, the other in 

 a slit cylinder of brass, were exactly equal in all their effects. 



The rotating anchor of a Saxton's machine, when in the 

 dark, and illuminated solely by the sparks it produces, appears 

 to stand still and exactly in the same position, whether the 

 anchor be turned slowly or as fast as possible. If there were 

 any lapse of time between the interruption of the current and 

 the appearance of the spark, the anchor would assume a dif- 

 ferent position, according to the rapidity of rotation. As this 

 however is not the case, it follows that the time elapsing be- 

 tween the interruption of the current and the appearance of 

 the spark is not measurable by this means. u ^ n vF 



VII. Note on the Composition of the Basic Sulphate of Mercury, 

 or Turpeth Mineral. By Robert Kane, M.D., M.R.I.A. 

 \ AM induced to bring forward, in the present form, the re- 

 suits of some analyses of the basic sulphate of mercury, 

 from the fact that its true composition does not appear to have 

 become generally known ; the best authorities, or at least those 

 most in the hands of students, giving different and mostly in- 

 correct views. Thus both in Christisori's * Dispensatory ' and 

 in Pereira's Materia Medica, this salt is stated to have the 



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