( 412 ) 



higher anhydrides we met with aw obstacle which p^e^'ented accurate 

 measurements. This was their small solubility in water. He always 

 noticed in their solutions a gradual increase in the electric conductive 

 power showing that they first dissolve as such before being con- 

 verted into acids, l)ut this increase was too small to allow the velocity 

 constant to be calculated. It is worthy of note that although when 

 boiled \NitIi water they form only globules which are but slowly 

 converted into acids, they are so hygro.scopic that they keep but a 

 short time unchanged when exposed to the air. This may, perhaps 

 be attributed to the fact that A\ater in tiie li(|uid condition consists 

 mainly of polymeric molecules, whereas in the state of vapour they 

 are normal. The anhy(h-ides of glutaric ajid succinic acid do not 

 show this peculiarity. 



But the higher anhydrides also (HJter in another res])ect from the 

 two first mentioned namely in tlieir molecular complexity. Deter- 

 minations of the boiling points of their solutions in acetone show 

 that they are much polymerised whilst the anhydrides of succinic 

 and glutaric acids l)ehave normally. This, perhaps, explains their 

 difficult solubility in water. 



(rroiiii///i'iL Lai). Univers. Xov. '03. 



Astronomy. — "■Invi'stujation of th' errors of the tables of the 

 moon of Hansen — Newcomb hi the i/ears 1895 — 1902." By 

 Dr. E. F. VAN DE Sande Bakhuyzen. (2'''^ Paper). 



(Communicated in the meeting of September 20 1903). 



14. After my previous paper under this title was read at the 

 meeting of the Academy of June 27, 1903, a preliminary communi- 

 cation on the investigation undertaken at Greenwich on similar lines 

 has also been published. Mr. P. H. Cowell who was occupied with 

 this work gave a summary of his results in "Tlie Ohserratovif' of 

 September 1903 in a paper under the title "Anahjsls of the errors 

 of the moon', which he kindly sent to me in advance of publication. 



Mr. CowELL utilized for his investigation the observations of right 

 ascension of the period 1883 — 1898. His method in the main agrees 

 with that used by Newcomb in his " fnvestk/ation\ which I had also 

 followed and our results for the years 1895 — 98 are substantially 

 in accordance. In the second place he compared his empirical results 

 with those derived from theory. 



This last part of Cowell's paper has drawn my attention to the 



