10 



DISCOVERY 



mctliods were developed. It should be noted that 

 the best results can only be obtained if the chlorosul- 

 phonic acid is heated suddenly to a temperature above 

 its boiling-point. If attempts arc made to vaporize 

 it by boiling, a partial decomposition takes place into 

 sulphuryl chloride and sulphuric acid ; the fonncr 

 decomposes very slowly with water vapour and is of 

 ver}' little use as a smoke-producing agent, whilst the 

 latter gradually accumulates in the boiling liquid. 

 In order to obtain complete success, it is furthermore 

 necessary that the vapour of the chlorosulphonic acid, 

 or its decomposition products, should come into 

 immediate contact with an excess of water vapour. 

 If attempts arc made to use chlorosulphonic acid 

 without supplying it with a sufficient amount of water 

 vapour, the smoke produced, even over the sea, is 

 liable to be somewhat thin on a dry day. 



The conditions necessary for success were satisfied 

 as follows, the particular methods of application being 

 due to Commander Brock : 



(a) The chlorosulphonic acid is fed as a fine spray 

 into the funnel of a destroyer. The temperature of 

 the waste products of combustion from the furnaces 

 is sufficient suddenly to vaporize the acid, and the 

 water vapour present completes the formation of the 

 cloud. 



{b) The chlorosulphonic acid is dripped into the 

 exhaust pipe of a petrol engine on a motor-launch or 

 coastal motor-boat. The effect is the same as in the 

 funnels. 



Both these methods were used with great success 

 in the raids on Zeebrugge and Ostend. Method (b) 

 was also adapted to land tanks, a number of these 

 being fitted up by a special experimental part}' sent 

 out from the Stratford Naval Station. 



Another method by which a very good smoke can 

 be obtained from chlorosulphonic acid is to force it 

 through a special spray nozzle by means of steam, 

 the acid and the steam being brought into contact just 

 at the orifice of the nozzle. 



It may be mentioned that the smoke produced by 

 chlorosulphonic acid, when sufficiently dilute, is hard 

 to distinguish from a sea mist, and no unpleasant effects 

 are noticeable on the face or when breathing it. 



Suggestions have often been received that ships 

 should be able to protect themselves by smoke screens 

 all the time they are in waters infested by enemy 

 craft. This, however, is not a feasible proposition at 

 present, since the carriage of the smoke materials 

 would necessitate a very large additional load on the 

 vessel. Such a project may ultimately be realized, 

 but it may be pointed out that practically all the readily 

 available substances capable of producing smoke are 

 now known ; whether satisfactory new substances 

 will be discovered in the future remains to be seen. 



The Modern Study of 

 Dreams 



By T. H. Pear, M.A., B.Sc. 



Pfo/fijor of Psj/clioloao tn tfie Vnlotnily o/ Manehetler 



" It's only a dream," is a comment which most of us 

 make frequently without realising what a challenge 

 our utterance is to the twentieth -century psychologist. 

 The educated scientific person of to-day generally 

 thinks of the dream as a trivial, absurd and nonsensical 

 structure. Yet it is interesting to note that the simple 

 mind, uninfluenced by the teachings of materialistic 

 science, has always believed in the dream's importance. 



And to-day there exists a band of workers who once 

 more regard the dream as deeply significant. They 

 were recruited from a field of study in which at present 

 there reign almost supreme those materialistic views 

 which would belittle the dream — the realm of medicine. 

 For doctors dehberately to choose to investigate 

 fantastic, meaningless, trivial mental phantoms like 

 dreams, when every medical school offers them rows 

 of solid brains, thousands of microscope slides with 

 nerve-cells and fibres already stained and mounted, 

 when all round them are people suffering from serious 

 mental disorders, when everyone knows that those 

 disorders are in some way connected with the brain ; 

 does this not seem like fiddling while Rome burns ? 



The answer is simple : yes, if one asserts that the 

 only way to discover the nature of mental occurrences 

 is by examining their underlying bodily mechanisms ; 

 no, if one believes that a mental event can be examined 

 by mental means, and explained in mental terms. 

 But, a critic may ask, and in all seriousness and 

 honest}', why not study the more orderly, more 

 manageable events of the mind ? 



An answer may be given by an example taken from 

 another field of science. Many years ago our critic 

 might have wondered at the strange behaviour of a 

 man who chose to fly a kite during a violent thunder- 

 storm. Even at the time the kite-flyer could have 

 given very cogent reasons for his action ; nowadays 

 every schoolboy understands that much of our modern 

 knowledge of electricity %vas made possible by this 

 apparently eccentric performance. But not only 

 does the explanation of the thunderstorm now form 

 part of an educated person's common sense, it helps 

 us also to understand the more difficult problems of 

 the workings of electricity in every -day situations. 

 So it is with the dream ; its processes are cruder than 

 those of the mind doing its every-day work ; it is 

 controlled by less complex forces ; its behaviour is 

 therefore simpler and often easier to comprehend. 



