On a new Variety of the Cohesion-Figures of Liquids. 425 



The value of the refraction corresponding to this difference of 

 level comes out 2' 33", viz. about T ^th of the angle at the centre 

 of the earth. 



In the Mesure d'un Arc du Par allele Moyen, the altitude arrived 

 at is 3798 m, 2, which corresponds to a refraction of 1' 46", or 

 2\j-th nearly of the angle at the centre. It is presumable that 

 the zenith-distance there given is rather too great ; for the alti- 

 tude of Monviso is 3836 metres according to Corabceuf, and 

 3840 metres according to the Etat Major Piemontais. In rea- 

 lity the distance between Turin and Monviso is too large for the 

 base of a hypsometrical triangle : an error of 1' in the zenith- 

 distance produces an error of about 19 metres in the altitude. 

 Even neglecting the refraction, the altitude of Monviso with 

 these data would only come out 3833*4 metres. 



Turin, April 1864. 



LXV. On a new Variety of the Cohesion-Figures of Liquids. By 

 Charles Tomlixson, Lecturer on Physical Science, King's 

 College School, London *. 



[With a Plate.] 



IN the Philosophical Magazine for October 1861 and March 

 1862, I have given a number of details respecting the 

 Cohesion-Figures of Liquids. The results of a more mature ex- 

 perience in this subject were laid before the Pharmaceutical 

 Society in February last, and are recorded in the Pharmaceutical 

 Journal for March and April f- The attention of persons in- 

 terested in the oil trade was also invited to the subject in a 

 paper read before the Society of Arts in March last, and printed 

 in the Society's Journal for the 4th of that month J. My object 

 in bringing the subject before these Societies was to endeavour 

 to enlist the sympathy of working chemists in carrying out the 

 practical application of this test. I had already established the 

 principle that liquids, under certain conditions, form charac- 

 teristic figures, which seemed likely to be useful in qualitative 

 analysis, if only as a rough and ready mode of identification, 

 although in some cases it seemed to admit of a rigour and 

 delicacy which could not be claimed for existing tests. What 

 was wanted for the further prosecution of the inquiry was, 

 (1) the collection of a large number of specimens, commercially 



* Communicated by the Author. 



t " On the Verification of Castor Oil and Balsam of Copaiba by means 

 of their Cohesion-Figures." 



X " On the Verification of Olive Oil by means of its Cohesion-Figure." 

 I may here remark that the figure of olive oil which accompanies my first 

 paper in the Philosophical Magazine was not obtained from a pure spe- 

 cimen, but from one adulterated with poppy-seed oil. 



