Weight of Caoutchouc and other Colloid Bodies. 39 



col. IV. the amount of depression, and in col. V. the rnole- 



T 



cular weight calculated by Eaoult's formula M= -r- ; where T is 



the molecular depression constant (in this case = 49), and A is 

 the depression given by 1 gram of the substance in 100 

 grams of solvent. These figures may be compared with col. 

 VI., which gives the molecular weight deduced from the 

 formula in col. II. 



Substance. 



Oil of Turpentine 

 Oil of Lemon 



» 



Cedrene 



oprene 



»» 



Caoutchene 



Heveene 



n 



Camphor 



Menthol 



j> 



Anethol 



Col. II. 



Col. III. 



Col. IV. 



Col. V. 



Col. VI. 





per cent. 











C 10-H-] G 



4-56 



159 



140-5 



136 





6-04 



217 



136-4 



136 





3-06 



112 



133-8 





C15H24 



3-89 



100 



190-8 



204 





471 



1-20 



192-3 





C 5 H 8 



330 



225 



71-9 



68 





2-20 



1-52 



70-9 





^10^16 



5-38 



2-01 



131-1 



136 



^20^32 



12-00 



232 



275 



272 





937 



1-85 



248 







7-68 



1-53 



246 





C 10 H 1B O 



4-69 



1-59 



144 5 



152 



10 H M O 



3-21 



0-93 



1691 



156 





4-93 



1-31 



184-4 





j> 



375 



107 



171-7 





C 10 H 12 O 



371 



1-29 



1410 



148 



This table shows not merely that the method is applicable 

 in the case of bodies of this description, but that the mole- 

 cular weights of the liquids in solution have the same relative 

 values as in the gaseous condition. 



"We then made experiments on caoutchouc, whose empirical 

 formula as usually given (C 10 H 16 ) would indicate a molecular 

 weight of 136, and we found that this was very far below 

 that deduced from our results, as shown in the following 

 table: — 



Substance. 



Weight in 100 

 grams of Solvent. 



Depression. 



Molecular 

 Weight. 



Cautchouc (a) ... 

 „ (ft) .- 



„ (<0 ... 



31 



8-8 

 14-6 



Scarcely observable. 

 0-11 



Extremely high. 



)» 



6504 



The caoutchouc used in solution (a) had been prepared 

 from Penang rubber, by the process described in our previous 



