Oct. 7, 1886] 
that carbon is deposited “electrolytically ” in the flashing 
process of heating in a hydrocarbon vapour; on p. 31 
that it requires “several” dynamos instead of one to 
yield an electromotive force of 2500 volts; on p. 27 that 
Ohm?’s law is true for the whole circuit only, and not for 
its parts ; on p. 91 that a shunt coil was first used in an 
arc lamp by Von Hefner Alteneck ; on p. 14 that “the 
velocity of a body falling through a vacuum” is “9°81 
metres in one second.” The definition of the ohm as 
originally fixed in 1862 by the Committee of the British 
Association was certainly not ‘‘equal to the resistance of 
a column of mercury of 104 centimetres in length and 
I square millimetre section,” as stated on p. 13. There 
is a grossly misleading extract from Merling’s work given 
in pp. 15 to 28 on the distribution of heat in an electric 
circuit. The old battery rule of arranging internal resist- 
ance equal to the external to get maximum current is 
trotted out, without a word of warning that this is an 
arrangement always to be avoided on account of its bad 
economy ; and as if this were not bad enough, an alge- 
braic corollary is added showing that this arrangement 
of maximum current is such as to make the maximum 
rate of output of heat in an external conductor of given 
resistance one-quarter of the output that there would be 
in the circuit if the battery were short-circuited. The 
student will at once draw the erroneous conclusion that 
at least three-quarters of the heat must necessarily always 
be wasted. But to make matters still worse, on p. 24, 
where the grouping of the battery is still under discussion, 
_ it is stated that in “no case can we obtain more heat,” in 
the conductor of given resistance, than the quarter pre- 
viously mentioned. This is entirely untrue ; for if the cells 
be grouped allin parallel so as to reduce the internal resist- 
_ ance to a minimum, then a very high percentage of the 
heat of the current—practically all of it—will be obtained 
in the conductor of high resistance, and the zincs of the 
_ battery will consume more slowly. There are several 
other matters to which exception must be taken: a crude 
assertion that a Gramme dynamo is better than a 
Siemens, which may have been true in 1878 ; crude state- 
ments true perhaps of a particular dynamo or a particular 
lamp, but not true of dynamos or lamps in general ; crude 
advice to makers to arrange their lamps so as to keep the 
resistance of the arc constant ; crude arguments in favour 
of using shunt-wound electro-magnets in arc lamps, all 
reasons being given except the right one. ‘Three times 
Dr. Werner Siemens’s name is erroneously given as 
Wilhelm Siemens. Lastly, electric engineers will be 
surprised to find amongst the practical hints nothing about 
the “striking” of the arc, or about the “hunting” action 
f lamps and its avoidance. It is to be hoped that these 
atters will be remedied when the author comes to re- 
rite his book for a second edition. 
‘ 
DISORDERS OF DIGESTION 
On Disorders of Digestion. By T. Lauder Brunton, 
M.D., F.R.S. (London : Macmillan and Co., 1886.) 
aes bookis a reprint of a series of disconnected papers 
which the author has contributed during the last thir- 
feen years to various periodicals and Societies, and is pre- 
NATURE 
543 
faced by the Lettsomian Lectures, “On Disorders of Diges- 
tion,” in which the author has collected together into one 
homogeneous whole many of the observations and illus- 
trations which he had introduced into his earlier papers. 
These lectures give a most admirable rész7é of the latest 
advances in our knowledge of the complicated processes 
of digestion and of mal-digestion, and the succeeding 
papers form a most interesting study of the gradual 
development of the author’s views. 
The main idea which runs throughout the whole work, 
and which the author more than any one else in this 
country has developed, is that, in mal-digestion, products 
are formed which in their passage through the liver dis- 
order its functions, and on reaching the general circula- 
tion act more or less as poisons, producing languor, list- 
lessness, heaviness of the limbs, great depression of 
spirits, and headache. 
Brieger especially has worked out both chemically and 
physiologically the products of digestion and decomposi- 
tion of food-stuffs. He has been able more or less suc- 
cessfully to separate several alkaloids which have most 
powerful effects when administered to animals. Several 
resemble very closely in their effects muscarin, the active 
principle which Prof. Schmiedenberg has separated from 
several species of mushrooms. This when administered 
to animals causes vomiting, purging, dyspnoea, and pros- 
tration, and it has been found that atropia is an efficient 
antidote. Many of these alkaloids are detained by the 
liver, and excreted with the bile into the intestine, again 
to be later on re-absorbed by the portal circulation, and 
may thus circulate in the portal system without ever enter- 
ing the general circulation. Lead, copper, and other 
minerals, when administered by the mouth, often circulate 
in this manner, and the same process is offered as an 
explanation of the trivial effects of curara when swallowed, 
while its subcutaneous injection is lethal. 
The author's views are corroborated by recent researches 
which allot a most important part in all digestive processes 
to bacteria and other micro-organisms. Cultivations carried 
on at Leipzig have shown that twenty-five micro-organisms 
are commonly found in the mouth, and that these under 
certain conditions may occasionally develop in various 
parts of the alimentary canal. Some develop large volumes 
of gas, and others lactic, caproic, caprylic, butyric acids, or 
other complex bodies during their growth. It is extremely 
probable, therefore, that the excessive multiplication of 
these micro-organisms generates the products of mal- 
digestion. A healthy condition of the alimentary canal 
and its secretions is inimical to their growth. A slight 
degree of acidity—less even than that normally present 
in gastric juice —is quite sufficient to check their 
growth. 
These experiments open up quite a new field for the 
treatment of dyspepsia : the actions of old well-established 
remedies receive a new explanation, and new drugs will 
be pressed into the service. 
Bitters are said to be beneficial because they check the 
secretion of mucus, which is a suitable nidus for some 
bacteria ; mineral acids, mercury and salicylic acid are 
more strongly recommended than ever because of their 
antiseptic properties ; charcoal, bismuth, and alkalies 
base their claim for support on their stimulation of the 
| gastric secretion. 
