Meteorological Observations, 319 



parts of distilled water ; agitate the mixture, allow it to remain for 

 some time, and then pour off tlie liquor from the cyanide of gold. 



To the mother water add 8 parts of cyanide of mercury, and 

 again evaporate to drj'ness , again add 192 parts of distilled water 

 to the dry residue, and again agitate ; suffer to remain, and pour off 

 from the cyanide of gold ; this may he repeated a third and a fourth 

 time, or until no more cyanide of gold of a fine colour is produced ; 

 the operation with the mother water may be repeated without its 

 being necessary to add cyanide of mercury every time. 



All the cyanide of gold obtained ought to be afterwards washed 

 with distilled water, till it comes away quite insipid, or until re- 

 agents show that it is entirely free from bichloride of mercury. 



Every time the mother water is used, it should be slightly acidi- 

 fied with a few drops of aqua regia ; without this the cyanide of 

 gold which separates would acquire by evaporation a yellow red- 

 dish colour. During the evaporation to dryness on the sand-bath, 

 the solution should be constantly stirred with a glass rod, till it ac- 

 quires a bright canary yellow colour ; the occurrence of this denotes 

 the formation of the cyanide of gold, mixed with bichloride of mer- 

 cury, and an excess of cyanide of mercury undecomposed ; these are 

 got rid of by washing with distilled water. 



The new Codex recommends the employment of pure cyanide of 

 potassium as being essential to the success of the operation ; but the 

 difficulty of procuring this salt in a pure state is well known. Be- 

 sides, the instability of this salt, even when it is kept in well- stopped 

 bottles, will always throw uncertainty on the results of the opera- 

 tion ; an objection which does not attach to the use of cyanide of 

 mercury. — Journal de Pharmacie, xxiv. p. 27. 



METEdROLOGICAL OBSERVATIONS FOR AUGUST 18.S8. 



Chisivick. — August 1. Very fine : heavy rain at night. 2. Rain. 3. Fine. 4, 

 Overcast : slight rain. 5. Cloudy. 6. Sultry, with showers. 7. Showery. 

 8, 9. Fine. 10. Overcast. 11 — 16. Very fine. 17. Hazy : slight rain. 18 — 20. 

 Very fine. 21. Showery. 22. Rain. 23. Showery. 24, Cloudy and fine. 

 25. Foggy : rain. 26, 27. Very fine. 28. Overcast : lightning at night. 

 29. Cloudy and fine. 30. Clear and dry. 31. Very fine. 



Boston. — August 1. Fine. 2. Cloudy: rain early a.m. 3. Rain. 4. Fine: 

 rain p.m. 5. Fine. 6. Cloudy : rain p.m. 7. Heavy rain with thunder and 

 lightning P.M. 8. Cloudy. 9. Fine ; rain p.m. 10. Cloudy : rain p.m. 11,12. 

 Cloudy. 13—15. Fine. 16. Cloudy. 17,18. Fine. 19,20. Windy. 21. 

 "Windy : rain early a.m. : rain p.m. 22. Windy : rain p.m. 23. Stormy. 

 24, 25. Fine. 26. Cloudy. 27. Cloudy : therm. 74° 6 p.m. 28. Cloudy. 

 29. Windy: rain early a.m. 30,31. Fine. 



Jipplegarlh Manse, Dunifrks-sldre. — August 1. Rain p.m. : warm and moist. 

 2. Fine day throughout. 3. Fine day : occasional showers. 4. Moist and 

 cloudy. 5. Heavy rain p.m. 6. Very heavy showers. 7- Showery all day. 

 8. Fine summer day : cool p.m. 9. Wet throughout. 10. Fair a.m. : wet 

 evening. 11. Drizzling rain a.m.: fair p.m. 12. Fair: shower p.m. 13. 

 Fair: shower at noon. 14. Fair throughout. 15. Fine clear day. 16. Tem- 

 perate: cool. 17. Beautiful summer day. 18. Cloudy: moist p.m. 19,20. 

 Showery all day. 21. Rainy all day : flood. 22. Showery all day. 2,3, 24. 

 Fair a.m. : shower p.m. 25. Very moist : rain p.m. 26. Fair : warm : cloudy. 

 27. Fair, but tlireatening. 28. Drizzling all day. 29. Clear and cool. 30. 

 Temperate. 31. Mild though cloudy. 



