270 



The Philippine Journal of Science 



1916 



in terms of grams weight. Table IV gives the results obtained by 

 averaging several tests. These figures are, of course, of value 

 simply for comparison, since they apply only to the conditions of 

 the experiment. 



Table IV. — Crtishing pressure for agar-agar blocks. 



Emulsion No. 



Agar-agar. 



Room tem- 

 perature, 

 28°C. (aver- 

 age of 3 

 tests) . 



Incubator 

 temperature, 

 37°C. (aver- 

 age of 2 



tests) . 



1 



Per cent. 

 1.5 

 1.75 

 2.0 

 2.25 

 2.5 



40-45 (?) 

 55.5 

 66 

 74 

 94.5 



37 



58.5 

 a60 

 •65 



89.5 



2 



3 



4 



5.- 





" Optimum. 



Specimens 3 and 4 are particularly useful for bacteriological 

 work; number 2 might be somewhat soft for use in planting 

 water. 



When the same test was applied to the gulaman extract, it 

 was found that the surface strength was very slight, amounting 

 to no more than from 5 to 8 grams. When, after prolonged 

 boiling, the whole was passed through a sieve — in itself a very 

 laborious process — and reboiled, the filtrate when cold gave pres- 

 sure readings of but 9 to 10 grams. In addition to being very 

 soft when cold, it appeared that an extract of this concentration, 

 when still hot, was not freely fluid, but was stiff enough to inter- 

 fere somewhat with cloth filtration. 



With the intention of obtaining constant concentration of the 

 extract, a quantity of the rubbed-through extract was dried to 

 constant weight at incubator temperature. This gave a dark, 

 hard, rather brittle material. 



Upon attempting to redissolve this dried material, it was 

 found that soaking for twenty-four hours restored a fragment 

 approximately to its original size, but that even after this length 

 of immersion, boiling rapidly for fifteen minutes effected only 

 partial solution. 



It was concluded that since the somewhat gelatinous extract 

 of gulaman dagat resembles ordinary agar-agar, but does not 

 have a similar peculiarly marked solidifying power, does not 

 melt so freely, and is not so fluid when melted and solidified at 

 a higher temperature, it is not suitable for use in bacteriological 

 work. 



