524 



PROFESSOR DITTMAR AND MR C. A. FAWSITT ON 



error introduced by allowing the dissolved air to remain, we made a determina- 

 tion at 14° 7 with air-free alcohol. The alcohol was boiled in the specific- 

 gravity bottle under an inverted (dry) condenser, then corked up while still 

 hot, brought to 14° 7, &c. The specific gravity of the air-free alcohol was 

 found equal to 079683, i.e., by 000016 higher than that of the original prepara- 

 tion. The difference barely emerged from the limit of unavoidable errors, and 

 Ave thought that we should probably risk more than we could possibly gain if 

 we adopted the more refined method as the method. 



Being in possession of a sufficient quantity of the kind of highly purified 

 alcohol which had served for the above determinations, we thought we ought 

 to supply to the chemical community what has hitherto been felt as a desider- 

 atum, namely, a set of tables giving the specified gravity of any aqueous methyl- 

 alcohol as a function of its percentage and temperature. We accordingly pre- 

 pared,' by exact gravimetric synthesis, a series of aqueous methyl-alcohols, 

 containing as nearly as possible 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 95 per cent, 

 by weight of absolute alcohol, and then determined their specific gravities in 

 each case at 0°, 9° 7, and 19° 7 C. The modus operandi was exactly the same 

 as that for the anhydrous alcohol. All the weighings were reduced to the 

 vacuum, and water of 4° adopted as the standard substance at all tempera- 

 tures. The numbers given as specific gravities accordingly may be read as 

 giving each the weight of 1 c.c. in grammes. All determinations were made in 

 duplicate — one with bottle No. I., another with bottle No. II. In the follow- 

 ing table of results, "p" gives the percentage of real CH 4 ; the three columns 

 D give 100,000 times the weight of 1 c.c, i.e., the value 4 S t for 2 = 0°, 9°7, and 

 19°7 respectively as a mean of two determinations. "A" is the deviation of 

 the two determinations from the mean : — 





Specific Gravities 4 S t of Aqueous Methyl- Alcohols. 





1 



p 



At 0°. 



At 9° -7. 



At 19°7. 



I) 



A 



D 



A 



D 



A 



95-062 



823 82 



4-5 



815 30 



20-5 



806 30 



6-5 



89-990 



837 46 



10-5 



829 00 



8-0 



820 44 



8-0 



79959 



863 54 



4-5 



855 48 



2 5 



847 24 



100 



70-003 



886 78 



6-0 



879 45 



4-5 



871 58 



65 



60-020 



908 95 



5-0 



901 95 



3-5 



894 75 



6-0 



50-022 



928 62 



0-5 



922 30 



0-5 



915 73 



3-5 



40-028 



945 85 



5-0 



940 45 



7-0 



934 67 



0-5 



30023 



960 39 



3-5 



956 11 



7-5 



951 58 



o-o 



20032 



972 46 



2-5 



970 00 



6-5 



966 67 



3-0 



10018 



984 22 



40 



983 42 



0-5 



981 54 



2-0 



5-008 



991 41 



00 



991 18 



3-5 



989 61 



1-5 



