470 REPORT—1883. 
5. On a Simplified Thermostat. By M. Wuittey Wittams, F.C.8. 
6, Some Experiments on Asbestos. By M. Wuirtey Wituams, F.C.S. 
7. On the Constitution of the Natural Fats. By J. ALrRED WANELYN 
and WituramM Fox, 
The received view of the constitution of the natural fats is that they are ethers 
of glycerin. Furthermore, it is generally maintained that the natural fats are tri- 
glycerides—that is to say, that they are fully saturated ethers of glycerin. The 
recognised exceptions are spermaceti (which is palmitate of cetyl) and cholesterine, 
the constitution of which is regarded as being uncertain. Our investigations have 
led us to the conclusion that among the natural fats must be enumerated a new 
class of compounds, viz. the ethers of iso-glycerins, and also that di-glycerides, or 
two-thirds saturated ethers of glycerin, are to be met with among the natural fats. } 
In collecting the actual experimental data relating to the natural fats, the 
authors have noted that, whilst the theoretical, or very nearly theoretical, yield of 
the fatty acids has frequently been obtained from a fat, the theoretical yield of the 
glycerin is missing. When a ton of tallow is subjected to the action of steam, 
they are informed that 10 cwt. of oleic acid, and 9 ewt. of stearic acid, and 1 cwt. 
of glycerin are the products, The theory requires that 2 cwt. of glycerin should be 
given. ‘ 
When Dupré subjected a weighed quantity of butter to the action of water at 
elevated temperatures, the sum of the fatty acids and the glycerin fell considerably 
short of the total required by the equation. 
The marked failure to get the theoretical yield of glycerin is a fact which de- 
mands an explanation. That explanation the authors are prepared to supply as 
follows :—‘ They hold that accompanying the glycerides there are iso-glycerides. 
From its structure an iso-glyceride can yield neither glycerin nor iso-glycerin when 
it is saponified, but must yield water and the corresponding fatty acid. 
The structural formula of common glycerin is— 
C,H,OH 
C,HOH 
CH,OH 
and glycerin can exist in an isolated condition. 
The structural formula of iso-glycerin is— 
C,(OH), 
ja | 
3 
and iso-glycerin exists only in its ethers, but cannot exist in an isolated condition. 
When an ether of iso-glycerin is saponified, the iso-glycerin is resolved into water 
and the corresponding fatty acid, thus— 
C,(OH), C,OOIL 
C,H, e C,H, +H,0 
CH, CH 
The iso-glycerins are a class of homologous bodies. The following are the formulas 
and names which the authors propose :— 
Methan-iso-glycerin, CH(OH),.—The triethylate of this lowest term of the 
series is one of the forgotten bodies of organic chemistry. Many years ago Kay 
discovered it. The ether got when chloroform acts upon ethylate of sodium is the 
body in question, which possesses the characteristic property of yielding no corre- 
sponding tri-atomic alcohol but yields the corresponding acid, which in this instance 
is formic acid. 
Ethan-iso-glycerin, CH,C(OH),.—Its ethers give acetic acid when saponified. 
Propan-iso-glycerin, CH,CH,C(OH),.—Its ethers give propionic acid when 
saponified. 
