Chapter 35
UNOFFICIAL METHODS
22. _Protein_
Determine nitrogen in 3 grams of the sample by the Kjeldahl or Gunning method. This gives the total nitrogen due to both the proteids and the caffein. To obtain the protein nitrogen, subtract from the total nitrogen the nitrogen due to caffein, obtained by direct determination on the separated caffein or by calculation (caffein divided by 3.464 gives nitrogen). Multiply by 6.25 to obtain the amount of protein.
23. _Ten Percent Extract--McGill Method_
Weigh into a tared flask the equivalent of 10 grains of the dried substance, add water until the contents of the flask weigh 110 grams, connect with a reflux condenser and heat, beginning the boiling in 10 to 15 minutes. Boil for 1 hour, cool for 15 minutes, weigh again, making up any loss by the addition of water, filter, and take the specific gravity of the filtrate at 15 C.
According to McGill, a 10-percent extract of pure coffee has a specific gravity of 1.00986 at 15 C., and under the same treatment chicory gives an extract with a specific gravity of 1.02821. In mixtures of coffee and chicory the approximate percentage of chicory may be calculated by the following formula:
(1.02821 - sp. gr.) Percent of chicory = 100 ------------------ 0.01835
The index of refraction of the above solution may be taken with the Zeiss immersion refractometer or with the Abbe refractometer.
With a 10-percent coffee extract, n_d 20 = 1.3377.
With a 10-percent chicory extract, n_d 20 = 1.3448.
Determinations of the solids, ash, sugar, nitrogen, etc., may be made in the 10-percent extract, if desired.
24. _Caffetannic Acid--Krug's Method_[187]
Treat 2 grains of the coffee with 10 cc. of water and digest for 36 hours; add 25 cc. of 90-percent alcohol and digest 24 hours more, filter, and wash with 90-percent alcohol. The filtrate contains tannin, caffein, color, and fat. Heat the filtrate to the boiling point and add a saturated solution of lead acetate. If this is carefully done, a caffetannate of lead will be precipitated containing 49 percent of lead.
As soon as the precipitate has become flocculent, collect on a tared filter, wash with 90-percent alcohol until free from lead, wash with ether, dry and weigh. The precipitate multiplied by 0.51597 gives the weight of the caffetannic acid.
[Ill.u.s.tration]
CHAPTER XVIII
PHARMACOLOGY OF THE COFFEE DRINK
_General physiological action--Effect on children--Effect on longevity--Behavior in the alimentary regime--Place in dietary--Action on bacteria--Use in medicine--Physiological action of "caffetannic acid"--Of caffeol--Of caffein--Effect of caffein on mental and motor efficiency--Conclusions_
By Charles W. Trigg
Industrial Fellow of the Mellon Inst.i.tute of Industrial Research, Pittsburgh, 1916-1920
The published information regarding the effects of coffee drinking on the human system is so contradictory in its nature that it is hazardous to make many generalizations about the physiological behavior of coffee.
Most of the investigations that have been conducted to date have been characterized by incompleteness and a failure to be sufficiently comprehensive to eliminate the element of individual idiosyncrasy from the results obtained. Accordingly, it is possible to select statements from literature to the effect either that coffee is an "elixir of life,"
or even a poison.
This is a deplorable state of affairs, not calculated to promote the dissemination of accurate knowledge among the consuming public, but it may be partly excused upon the grounds that experimental apparatus has not always been at the level of perfection that it now occupies. Also, to do justice to some of the able men who have interested themselves in this problem, it should be said that some of their results were obtained in researches, distinguished by painstaking accuracy, which have effected the establishment of the major reactions of ingested coffee.
_The Physiological Action of Coffee_
Drinking of coffee by mankind may be attributed to three causes: the demand for, and the pleasing effects of, a hot drink (a very small percentage of the coffee consumed is taken cold), the pleasing reaction which its flavors excite on the gustatory nerve, and the stimulating effect which it has upon the body.
are considered under separate headings.
Coffee may be considered a member of the general cla.s.s of adjuvant, or auxiliary, foods to which other beverages and condiments of negligible inherent food value belong. Its position on the average menu may be attributed largely to its palatability and comforting effects. However, the medicinal value of coffee in the dietary and _per se_ must not be overlooked.
The ingestion of coffee infusion is always followed by evidences of stimulation. It acts upon the nervous system as a powerful cerebro-spinal stimulant, increasing mental activity and quickening the power of perception, thus making the thoughts more precise and clear, and intellectual work easier without any evident subsequent depression.
The muscles are caused to contract more vigorously, increasing their working power without there being any secondary reaction leading to a diminished capacity for work. Its action upon the circulation is somewhat antagonistic; for while it tends to increase the rate of the heart by acting directly on the heart muscle, it tends to decrease it by stimulating the inhibitory center in the medulla.[188]
The effect on the kidneys is more marked, the diuretic effect being shown by an increase in water, soluble solids, and of uric acid directly attributable to the caffein content of the coffee taken. In the alimentary tract coffee seems to stimulate the oxyntic cells and slightly to increase the secretion of hydrochloric acid, as well as to favor intestinal peristalsis. It is difficult to accept reports of coffee accomplis.h.i.+ng both a decrease in metabolism and an increase in body heat; but if the production of heat by the demethylation of caffein to form uric acid and a possible repression of perspiration by coffee be considered, the simultaneous occurrence of these two physiological reactions may be credited.
The disagreement of medical authorities over the physiological effects of coffee is quite p.r.o.nounced. This may be observed by a careful perusal of the following statements made by these men. It will be noticed that the majority opinion is that coffee in moderation is not harmful. Just how much coffee a person may drink, and still remain within the limits of moderation and temperance, is dependent solely upon the individual const.i.tution, and should be decided from personal experience rather than by accepting an arbitrary standard set by some one who professes to be an authority on the matter.
A writer in the _British Homeopathic Review_[189] says that "the exciting effects of coffee upon the nervous system exhibit themselves in all its departments as a temporary exaltation. The emotions are raised in pitch, the fancies are lively and vivid, benevolence is excited, the religious sense is stimulated, there is great loquacity.... The intellectual powers are stimulated, both memory and judgment are rendered more keen and unusual vivacity of verbal expression rules for a short time." He continues:
Hahnemann gives a characteristically careful account of the coffee headache. If the quant.i.ty of coffee taken be immoderately great and the body be very excitable and quite unused to coffee, there occurs a semilateral headache from the upper part of the parietal bone to the base of the brain. The cerebral membranes of this side also seem to be painfully sensitive, the hands and feet becoming cold, and sweat appears on the brows and palms. The disposition becomes irritable and intolerant, anxiety, trembling and restlessness are apparent.... I have met with headaches of this type which yielded readily to coffee and with many more in which the indicated remedy failed to act until the use of coffee as a beverage was abandoned.
The eyes and ears suffer alike from the super-excitation of coffee.
There is a characteristic toothache a.s.sociated with coffee.
In apparent contradiction of this opinion, Dr. Valentin Nalpa.s.se,[190]
of the Faculty of Medicine of Paris, states:
When coffee is properly made and taken in moderation, it is a most valuable drink. It facilitates the digestion because it produces a local excitement. Its princ.i.p.al action gives clear and stable imaginative power to the brain. By doing that, it makes intellectual work easy, and, to a certain extent, regulates the functions of the brain. The thoughts become more precise and clear, and mental combinations are formed with much greater rapidity.
Under the influence of coffee, the memory is sometimes surprisingly active, and ideas and words flow with ease and elegance.... Many people abuse coffee without feeling any bad effect.
Discussing the use and abuse of coffee, I.N. Love[191] says:
The world has in the infusion of coffee one of its most valuable beverages. It is a prompt diffusible stimulant, antiseptic and encourager of elimination. In season it supports, tides over danger, helps the appropriate powers of the system, whips up the flagging energies, enhances the endurance; but it is in no sense a food, and for this reason it should be used temperately.
Also Dr. Jonathan Hutchinson[192] makes the following weighty p.r.o.nouncement:
In reference to my suggestion to give children tea and coffee. I may explain that it is done advisedly. There is probably no objection to their use even at early ages. They arouse the dull, calm the excitable, prevent headaches, and fit the brain for work.
They preserve the teeth, keep them tight in their place, strengthen the vocal chords, and prevent sore throat. To stigmatize these invaluable articles of diet as "nerve stimulants" is an erroneous expression, for they undoubtedly have a right to rank as nerve nutrients.
But Dr. Harvey Wiley[193] comes forth with evidence on the other side, saying:
The effects of the excessive use of coffee, tea, and other natural caffein beverages is well known. Although the caffein is combined in these beverages naturally, and they are as a rule taken at meal times, which mitigates the effects of the caffein, they are recognized by every one as tending to produce sleeplessness, and often indigestion, stomach disorders, and a condition which, for lack of a better term, is described as nervousness.... The excessive drinking of tea and coffee is acknowledged to be injurious by practically all specialists.
Dr. V.C. Vaughn,[194] of the University of Michigan, speaking of tea and coffee, expresses this opinion:
I believe that caffein used as a beverage and in moderation not only is harmless to the majority of adults, but is beneficial.
This verdict is upheld by the results of a symposium[195] conducted by the _Medical Times_, in which a large majority of the medical experts partic.i.p.ating, among whom may be enumerated Drs. Lockwood, Wood, Hollingworth, Robinson, and Barnes, agreed that the drinking of coffee is not harmful _per se_, but that over-indulgence is the real cause of any ill effects. This is also true of any ingested material.
Insomnia is a condition frequently attributed to coffee, but that the authorities disagree on this ground is shown by Wiley's[196] contention, "We know beyond doubt that the caffein (in coffee) makes a direct attack on the nerves and causes insomnia." While Woods Hutchinson[197]
observes: