4Q2 THE POPULAR SCIENCE MONTHLY 



the design woven into the cloth or dyed or printed upon it; nothing 

 (such as arsenic antimony, or lead) of a poisonous nature or in any 

 way deleterious to the skin, may be used and the fireproofing must be 

 permanent, that is to say, it must not be removed, even in the case of 

 a garment which may possibly be washed fifty times or more. Further- 

 more, in order that it may have a wide application, the process must be 

 cheap. What was really to be aimed at was to treat the flannelette in 

 such a way that it acquired practically the properties of wool, which, 

 for all ordinary purposes, may be taken as the standard of a safe 

 material. Apart from the other conditions which I have laid down, 

 when one considers the vigor with which the ordinary washerwoman 

 scrubs garments with soap, not infrequently with the assistance of the 

 scrubbing brush, and takes into account the wonderful mechanical 

 appliances now so largely used for washing clothes with the least 

 expenditure of time, it will not be thought surprising that the discovery 

 of a process of fireproofing sufficiently permanent to resist all these 

 conditions seemed to me at first to be almost an impossibility. 



In describing the course of the research, I may perhaps be allowed 

 to give a brief sketch of the development of the subject and to outline 

 the reasoning which led to the institution of the various experiments. 

 Some idea of the difficulty of the subject will be gathered when I say 

 that Mr. Samuel Bradbury, who so ably assisted me in the work and 

 has kept a record of each experiment, tells me that upwards of 10,000 

 separate burning tests were made before the solution of the problem 

 was reached. Besides these, a great number of further experiments 

 have since been made to see whether an even cheaper process than that 

 which has now been in commercial use for nearly ten years could be 

 discovered. 



I suppose that every one would agree that, at the outset of the 

 experiments, the condition which seemed most difficult of realization 

 was that of finding a substance which not only fireproofs, but which 

 during the process becomes so permanently fixed that it will prove to 

 be absolutely resistant to washing with soap and water or mechanical 

 rubbing. Obviously the substance which is to fulfil these conditions 

 must, in the first place, be insoluble in water and secondly in order 

 that it is not liable to be removed by mechanical rubbing and does not 

 render the cloth dusty, it must be fixed in the fiber and not be merely 

 on the surface. I have already explained that when calico is dipped 

 in a dilute solution of sodium tungstate, and then dried the material 

 possesses in a remarkable degree the property of resisting flame and 

 then again alum has often been recommended for the same purpose. 

 Now when solutions of sodium tungstate and alum are mixed, an in- 

 soluble aluminum tungstate is produced and it is clear that, if this 

 insoluble salt could be fixed in the fiber, the material would certainly 



