TEMPERED GLASS. 555 



other things he, some years since, conceived tlie idea of rendering 

 glass less susceptible to fracture, either from blows or from rapid al- 

 ternations of heat and cold. The early training of his mind naturally 

 led him to look to mechanical means for the accomplishment of this 

 end; and he, in the first place, set himself a purely mechanical prob- 

 lem to solve. He thought as did Sir Joseph Whitworth with re- 

 gard to steel that by submitting glass when in a soft or fluid condi- 

 tion to great compressive power, he should force its molecules closer 

 togethei', and, by thus rendei-ing the mass more compact, the strength 

 and solidity of the material would be greatly increased. This was 

 not an unreasonable line of argument, inasmuch as the fragility of 

 glass results from the weakness of the cohesion of its molecules. Suc- 

 cess, however, did not follow experiment, and the mechanical problem 

 was laid aside unsolved. 



M. de la Bastie, however, continued to regard the question from 

 an engineering point of view, and turned his attention to another 

 method of treatment. Aware that the tenacity of steel was increased 

 and that a considerable degree of toughness was imparted to it by 

 dipping it, while hot, into heated oil, he experimented with glass in a 

 similar manner. The results were sufficiently successful to encourage 

 him to persevere in this direction, and, by degrees, to add other fatty 

 constituents to the oil-bath. Improved results were the consequence; 

 and they continued to improve until at length, after several years of 

 patient research and experiment, De la Bastie succeeded with a bath 

 consisting of a mixture of oils, wax, tallow, resin, and other similar 

 ingredients in producing a number of samples of glass which were 

 practically unbreakable. As may be supposed, there were other con- 

 ditions ujDon which success depended besides the character and pro- 

 portions of the ingredients constituting the bath. M. de la Bastie, 

 not being a glass-manufacturer, purchased sheets of glass, as well as 

 glass articles, which he heated in a furnace or oven, to a certain tem- 

 perature, and transferred to the oleaginous bath, which was also heat- 

 ed to a given temperature. These questions of relative temperature, 

 therefore, had to be worked out ; and De la Bastie had further to de- 

 termine, very precisely, the condition of the glass most favorable for 

 the proper action of the bath upon it. This he found to be that point 

 at which softness or malleability commences, the molecules being then 

 capable of closing suddenly together, thus condensing the material 

 when plunged into a liquid at a somewhat lower temperature than 

 itself, and inclosing some portion of the constituents of the bath in 

 its opened and susceptible pores. Having determined all these condi- 

 tions, and constructed apparatus, M. de la Bastie was enabled to take 

 ordinary glass articles, and pieces of sheet-glass, and to toughen them 

 so that they bore an incredible amount of throwing about and ham- 

 mering without breaking. Just, however, as De la Bastie had per- 

 fected his invention, he lost the clew to success, and for two years he 



