CONTENTS XVII 
ONNEs (H. KAMERLINGH) and Sopuus Weger. Investigation of the viscosity of gases 
at low temperatures. IT. Helium. 1396. IIT. Comparison of the results obtained 
with the law of corresponding states. 1399. 
OOSTERHUIS (B.) and H. KAMERLINGH ONNES. Magnetic researches. VI, On paramag- 
__netism at low temperatures. 322. VII. 965. VIII. On the susceptibility of gaseous 
oxygen at low temperatures. 1404. 
orBIT of the periodic comet Houmes (Researches on the) and on the perturbations 
of its elliptic motion. V. 192. 
ORBITOIDS of Sumba. 461. 
ORNSTEIN (L. S.). Accidental deviations of density in mixtures. 54. 
— On the thermodynamical functions for mixtures of reacting components. 1100. 
— The diffraction of electromagnetic waves by a crystal. 1271. 
OxYGEN (On the susceptibility of gaseous) at low temperatures. 1404. 
OXYHALOIDs (On a few). 52. 
PAIRS OF POINTS (On the correspondence of the) separated harmonically by a twisted 
quartic curve. 918. 
PANCREAS (Influence of some inorganic salts on the action of the lipase of the). 336. | 
PANNEKOEK (A.). The variability of the Pole-star. 1192, 
PARAFFIN (Oxydation of petroleum,) paraffin-oil and benzine by microbes. 1145. 
PARALLEL STRUCTURE (On the formation of primary) in lujaurites. 734. 
PARAMAGNETISM (On) at low temperatures. 322. 965. 
Pathology. ERNESTINE DE NEGRI and W. G. Mieremet: “On a micro-organism grown 
in two cases of uncomplicated Malignant Granuloma”. 765. 
PEKELHARING (C. A.). Influence of some inorganic salts on the action of the 
lipase of the pancreas. 336. 
— presents a paper of Dr. W. EK. RiNGER and H, van Trict: “Influence of the 
reaction upon the action of ptyalin”. 799. 
PELAPIS-ISLANDs (On rhyolite of the). 347. 
PENICILLIUM GLAUCUM (Mutation of) and Aspergillus niger under action of known 
factors. 124. 
PERIODIC CHANGE (The) in the sea-level at Helder in connection with the periodic 
change in the latitude. 1441. 
PERTURBATIONS (Researches on the orbit of the periodic comet Hormrs and on the) 
of its elliptic motion. V. 192. 
PETREFACTIONS of the earliest European Angiosperms. 620. 
PETROLEUM (Oxydation of), paraffin, paraffin-oil and benzine by microbes. 1145. 
pHacocytosis (The effect of fatty acids and soaps on). 1290. 
PHOSPHORUS (On the system). 885. 
PHOTOTROPISM (The influence of temperature on) in seedlings of Avena sativa. 
1170. 
PHYLLOTAXIS (On the connection between) and the distribution of the rate of growth 
in the stem. 1015. 
Physics. T. van LOHUIzZEN: “Series in the spectra of Tin and Antimony”. 31. 
— L. S. Ornstein: “Accidental deviations of density in mixtures”. 54. 
97 
Proceedings Royal Acad. Amsterdam. Vol. XVI. 
