550 SPECIAL METHODS OF DISCOVERY. 



we look only for what we expect, and we see only what we 

 look for, and fail to see what we do not look for, even 

 though it be present, unless it exists in a conspicuous 

 degree. I have used this method with perfect success on 

 several occasions. By subjecting a large number of metal- 

 lic solutions of various kinds to electrolysis, I found what 

 is called ' explosive or amorphous antimony,' and by sepa- 

 rately immersing a great variety of substances in lique- 

 fied hydrochloric acid gas, I discovered that caustic lime, 

 after being immersed during several days in that liquid 

 under a pressure of about 1,100 Ibs. per square inch, 

 which forced the acid into all its pores, perfectly retained 

 its alkalinity contrary to all anticipations derived from 

 previous chemical knowledge, i.e. notwithstanding the 

 powerful tendency of the hydrogen of the acid to unite 

 with the oxygen of the lime and form water, the great pre- 

 disposition of the chlorine to combine with the calcium to 

 form a salt, and the extreme avidity of that salt to unite 

 with the newly-formed water. In a similar way, by sub- 

 jecting large numbers of substances to contact with various 

 liquefied gases, e.g. carbonic anhydride, ammonia, cyano- 

 gen, and hydrocyanic acid, several other new and interest- 

 ing results were obtained. Many other similar researches 

 with other liquefied gases remain yet to be made. 



/. By examining the effects of a particular force 

 upon substances. As there are various forces, and many 

 ways of applying them, this method is extremely varied 

 and extensive, and may be divided into a number of 

 more limited ones; and to describe all the discoveries 

 which have been made by means of it, would require a 

 treatise to be written upon each of the physical and 

 chemical sciences. 



Various discoveries have resulted from applying pres- 

 sure to substances. The well-known law of Boyle and 



