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Table V. Potassium Perchlorate and Nitrate resist 

 reduction by Ferrous salts for five minutes at a boiling 

 temperature. 



Table VI. Potassium Chlorate is rapidly reduced by 

 Ferrous solution at higher temperatures . . . 249 



Table \ II. Effect of Dilution on the reduction of 

 Potassium Chlorate at ordinary temperatures. 



No. 14. THE SUNSETS OF AUTUMN, 1883. OBSERVED AT SEA 

 IN THE CABLE-SHIP "DACIA." [From The Times, 



December 25, 1883] ....... 250 



At the invitation of my old friend, the late Robert 

 Kayo Gray, then the manager of the Cable Department 

 of the India Rubber, Gutta Percha and Telegraph 

 Works Co. (Limited) of Silvertown, I joined him on the 

 "Dacia" which was commissioned to survey the route 

 and to lay the cable to connect the Canary Islands with 

 Spain. 



It was while the cable staff were accomplishing the 

 difficult operation of laying the shore-end to connect up 

 the island of La Palma with the deep-sea cable that 

 I was able to make the observations on the changing 

 visibility of the Peak of Teneriffe, seventy miles distant, 

 before and after sunrise. This was also an admirable 

 station from which to study the sunrises, and it will be 

 seen in the paper that they exhibited no unusual feature 

 on the ten consecutive mornings on which I observed 

 them from that station. 



The observation of the alternating visibility and 

 eclipse of the Peak of Teneriffe every morning furnishes 

 an excellent example on a large scale of what is well 

 known to every pilot. When he is steering a vessel 

 through a fog after dark, nothing handicaps his efforts 

 so much as the lights which his ship is obliged to carry, 

 and the more powerful they are the more difficult be- 

 comes his task. 



In a weak diffused light the fog particles are nearly 

 invisible and affect the visibility of objects behind it 

 only by their mass; when, however, these particles are 

 illuminated by a strong direct light, the light which 

 they reflect may be relatively so intense, even in the 

 case of the very thin haze of a depth of seventy miles 

 above cited, as to dazzle the eye and prevent it seeing 



