December 29, 192 1] 



NATURE 



cxli 



INFRA-RED 

 SPECTROMETER 



for experiments in 

 connection with the 



RADIATION THEORY OF 

 CHEMICAL ACTION. 



Reading directly in 

 wave-lengths from 

 500 /i/i to 9000 H-f^. 



Full particulars on request from 

 the Makers : 



ADAM HILGER Ltd. 



75a Camden Road, London, X.W.I 



Telephone : North 1677 and lo/S. 

 Telegrams : Sphericity, Phone, London. 



TRADE 



MARK 



PURE REAGENTS FOR RESEARCH 



We are Manufacturers of 



SYNTHETIC ORGANIC INDICATORS 



VOLUMETRIC SOLUTIONS 



MICROSCOPIC REAGENTS 



MOUNTING MEDIA 



TEST PAPERS 



ANALYTICAL REAGENTS " A.R." 



The Catalogue of our Chemical Products, comprising 



upwards of 2400 chemicals for research and analysis, 



can be obtained on application. 



THE BRITISH DRUG HOUSES, Ltd. 



Makers of Fine Chemicals. 



Graham Street, City Road, London, N.l. 



Chemical Works: Wharf Road. London. N.l. 



THE 



PRISM THEATRE GLASS 



TELEATER 



Large field of view 



Exceptional light transmitting power 



Critical definition 



Descriptive pamphlet on request 



DISTRIBUTORS 



J. W. ATHA & CO. 

 8 Southampton Row, London, W.C. 1 



