experiments developing the present invention were conducted with a variety of organic fatty acids applied to glass containers at a variety of temperatures . in fabricating the test containers , two furnaces were used . the first was a gas fired softening furnace capable of temperatures to 2500 ° f . ± 50 ° variation . the second was an electrically heated annealing furnace capable of temperatures to 1900 ° f ., holding ± 20 ° variations . the experimental containers were hand blown spheres because of straightforward analysis of a near spherical shape . approximate ranges of thicknesses tested range from 0 . 009 inch wall to 0 . 150 inch wall and diameter ranges of approximately 1 . 25 inches to 2 . 5 inches . the glass composition is basic lime - soda glass , also known as silicon glass , as is commonly found in a variety of beverage bottles : table 1______________________________________chemical composition of lime glass used infabricating evaluation shapes______________________________________ percent s . sub . 1 o . sub . 2 73 . 0 % na . sub . 2 o 16 . 0 % k . sub . 2 o 1 . 4 % cao 5 . 0 % mgo 3 . 5 % fe . sub . 2 o . sub . 3 0 . 1 % ______________________________________ in the laboratory , this composition retained total collapsing temperature of 1292 ° f . this is approximately the same temperature as the softening point . the annealing range for this composition was 900 °- 950 ° f . it is believed that the invention is not dependent on the limited glass formula here used , but is widely applicable to all formulas of glass . the organic fatty acids used in the experiments are glutamic , stearic and behenic acids , selected for their commercial availability . experiments were conducted both with the free fatty acids and with the fatty acids combined with an inert carrier . the inert carriers tested included paraffin base waxes such as beeswax . testing of experimental results was made by a standard drop test . the experimental glass shapes were dropped from measured heights into a box having a concrete floor 1 inch thick . in this way , a qualitative determination of glass strength could be reliably made . some representative results of the drop test follow . in all experiments , untreated glass spheres failed at a drop height of 2 feet . table 2______________________________________strength of glass as expressed by drop heightshowing the effect of different fattyacids v . temperature of application ( no carrier ) temperature drop heightacid (° f .) ( ft .) ______________________________________behenic 1000 11 . 0 &# 34 ; 1150 10 . 5 &# 34 ; 1400 8 . 0stearic 1000 9 . 0 &# 34 ; 1150 8 . 0 &# 34 ; 1400 6 . 0glutamic 1000 6 . 25 &# 34 ; 1150 6 . 0 &# 34 ; 1400 4 . 5______________________________________ table 3______________________________________strength of glass as expressed by drop heightshowing the effect of different fatty acidsin a beeswax carrier v . temperature of application temperature drop height (° f .) ( ft .) ______________________________________behenic 900 9 . 0 &# 34 ; 1000 11 . 0 &# 34 ; 1550 10 . 0stearic 900 7 . 0 &# 34 ; 1000 9 . 0 &# 34 ; 1550 9 . 0glutamic 900 6 . 0 &# 34 ; 1000 8 . 0 &# 34 ; 1550 7 . 0______________________________________ table 4______________________________________combined effect of stearic and behenic acids in abeeswax carrier on the strength of glass expressedby drop height v . temperature of application______________________________________temperature (° f .) drop height ( ft .) ± 1 / 2 ft . ______________________________________ 900 10 . 51000 13 . 51100 15 . 01200 14 . 01300 13 . 0______________________________________ as suggested by these representative results , the best overall temperature found in the experimental work was approximately 1100 ° with 1000 ° to 1300 ° being the presently preferred temperature range . some results suggest that a lower temperature closer to 900 ° may be better . the probable minimum temperature for achieving substantial results is approximately 700 ° and the maximum is the decomposition temperature of the fatty acid being used , about 1600 ° for example . the experimental method of making the treated glass is to heat glass to a molten temperature of 1900 ° and then blow the desired shape in a mold lined with rubber which has been soaked with the fatty acid . the shape is thus formed and treated at the same time . other suitable methods include applying the fatty acid to the glass after the shape is formed , by spray for example . thus , glass containers already manufactured could be strengthened by this method . the exact chemical reaction responsible for the glass strengthening has not been investigated , but it is believed that the organic fatty acid having the general structure ## str1 ## is surface active and chemically reacts with atoms of the glass to form a strengthened surface , thereby strengthening the tips of the microcracks and preventing further crack propagation when the glass is under load . it is further believed that the reactive - oh group reacts with silicon , calcium , or another constituent element of glass to chemically attach the fatty acid molecule to the glass surface . thus , the coating is able to resist soaking in water and in both acid and alkaline solutions . this chemical combination with surface atoms of the glass is termed chemisorption , and is broadly expected to occur with glass of virtually all formula compositions . the lime - soda glass used for the experimental work is merely a cheap and commonly used form , and therefore an important first example of the utility of the invention . any fatty acid is believed to produce the desired strengthening , although with varying success . behenic acid proved most successful and also is the longest chained of the three acids tested . the probable reason is that the longer chained molecules are more unstable , hence more reactive , and undergo the desired combination with the glass with less applied energy . it is noted that greater drop strengths were achieved with a mixture of fatty acids . experiments revealed that treated shapes fractured more readily after repeated drops , suggesting that new microcracks were generated in dropping and these new cracks provided points for crack propagation and eventual failure of the shape . a conventionally applied coating to protect the glass surface , a plastic for example , helped the shapes to retain the effectiveness of the chemisorbed coating , apparantly by preventing the formation of new microcracks .