4 oo THE POPULAR SCIENCE MONTHLY 



Again, unless the materials or garments after washing, have been dried 

 before immersion in the fireproofing solution, this solution can not be 

 kept uniform since, each garment being wet when put in leaves the so- 

 lution weaker than before and therefore of less protective value. To 

 dry each garment between the washing and the fireproofing entails so 

 much trouble and labor and expense that it would obviously prevent 

 any general adoption of the practise. Although the substances I have 

 mentioned and the salts of ammonium in particular, possess in a high 

 degree the property of rendering material fireproof, there is one sub- 

 stance which confers the property of resisting fire to cotton goods in 

 such a remarkable degree that it has long attracted attention and must 

 be specially mentioned, and that is sodium tungstate. 



A piece of muslin soaked in a weak solution of sodium tungstate 

 and then dried is practically non-inflammable but unfortunately this 

 salt is again so excessively soluble in water that a mere rinsing in clean 

 water is sufficient to remove it completely and the fireproofing is lost. 

 And this applies not only to sodium tungstate but also to all the other 

 salts which have, from time to time, been recommended for fireproofing 

 purposes; the result is not permanent because the proofing is at once 

 removed when the goods are washed in the ordinary way. 



The problem on which I was engaged for several years and which 

 has now been successfully solved, in a very simple manner, was that of 

 attempting to discover some process which not only made the goods 

 non-inflammable but also permanently non-inflammable, and the re- 

 searches on this subject were originally started in connection with 

 flannelette, a material very largely and widely used for clothing, espe- 

 cially by the poorer classes, and one of the most, if not the most, in- 

 flammable of all cotton goods. 



Flannelette may be briefly described as a kind of calico the surface 

 of one or both sides of which has been " carded " or " raised " into a 

 nap, the result being that the surface of the calico becomes covered with 

 a fluff of minute fibers somewhat resembling a thin layer of cotton wool. 

 This effect is produced by subjecting the surface of the calico to the 

 action of a series of revolving rollers covered with a vast number of 

 small pieces of sharp steel wire, which tear up the surface, and the 

 material is passed over these rollers over and over again until the re- 

 quired amount of nap has been raised. The result of this superficial 

 covering of nap is — as everybody who has handled flannelette will 

 know — a warm, pleasant and cosy feel and this is no doubt due to a 

 covering of air being imprisoned by the minute fibers thus producing 

 a layer which acts as a non-conductor much in the same way as in the 

 case of flannel. 



In the first two samples in the little book which you each received 

 as you entered the hall are calico and flannelette and you will notice at 



