Lloyd's Concentrator and Extractor, or Cold Still

By Francis Brinker, N.D.
University of Arizona

Reprinted from Lloydiana Volume 8, Number 4, Fall 2004, pages 2-4

The early 20th century was a time of active attempts in America to improve the quality of pharmaceutical extracts of botanicals. In the process of manufacturing concentrated extracts, it was also a commercial concern to effectively recover the solvent being removed. This greatly reduced the cost of production, since alcohol and other organic solvents were a large portion of the expense involved in extract manufacturing. Other significant issues of concern were management of space, time, and workforce involved with the necessary procedures. The desirability of continuous extraction to exhaust the dried plant (commonly referred to by pharmacists then as the drug rather than the herb) led to the development of devices to recirculate the solvent. A still was situated below the percolator to evaporate the solvent. The vaporized solvent was then piped to a condenser situated above the percolator, allowing the solvent to then be fed into the percolator for re-use.

This efficient and thorough process was exemplified by the Soxhlet extractor. One such commercial device, known as Lewin's extraction apparatus, used a hot solvent to exhaust the drugs. The combination of a continuously running percolator with an attached still recycling solvent into a condensor situated above the percolator allowed for efficient use of space and materials. [Pictured at left: John Uri Lloyd with his first extractor, n.d. From Lloyd Library and Museum, John Uri Lloyd Papers , Collection 1, Box 21, Scrapbook #6.]

Pharmacists recognized the destructive influences of heat applied to extracts diminished the efficacy of a number of products that were concentrated through the process of evaporating the solvent (menstruum). This was true in the case of the pharmacopeial fluid extracts. After the drug (marc) was soaked (macerated) with an initial volume of menstruum for 48 hours, it was then allowed to slowly percolate through the marc. This first percolate solution was set aside as the reserve, usually about 4/5 of the final total volume. Further solvent was then percolated through the marc to exhaust it of its active components. However, this second extraction resulted in a dilute solution that required evaporation by heating to concentrate it to a volume that supplied the final 1/5 of the total. This was then added to the reserve in an attempt to achieve a standard strength of solution. Fluid extracts were thus processed so that each milliliter volume represented one gram dry weight of the drug extracted (a 1:1 extract). However, the heating of the second percolate and the mixing of this concentrate with the reserve led to many problems affecting quality.

John Uri Lloyd was fully aware of issues that plagued fluid extract manufacturing. He received his first of three prestigious Ebert Prizes in 1882 for his paper on "Precipitates in Fluidextracts." Lloyd then served as a special member of the United States Pharmacopeial Commission of 1890. Though Lloyd did manufacture some official USP fluid extracts to satisfy doctors' requests, he preferred in most cases to follow his own procedures modified specifically for each plant, so as to maximize extract quality and therapeutic efficacy. He sought to discover the best means of extracting active constituents of plant drugs to produce medicinal forms with as little change as possible from natural combinations as found in plant tissues. This involved decades of experimental study. For example, he operated outside the pharmacopeial norms in determining whether a plant was best extracted when fresh, partially dried, or dried. Thus he sought to optimize his unique line of 1:1 strength Specific Medicines. Likewise, in the process of concentrating liquid extracts he ventured to minimize the application of heat.

In developing his concentrator and extractor, he applied the then-novel principle of applying heat to the surface, rather than the bottom, of the liquid. This was done by an arrangement of pipes containing live steam that passed through the concentrator near the surface of the solution. This allowed for the evaporation of the volatile solvents without heating the entire extract. The percolator, concentrator, and condenser were attached in a series by a system of pipes transfering the extract and solvent, together with pipes conducting steam and cold water. To the uninitiated, the design appears to be an unnecessarily complicated construction. However, the apparatus was devised to assure superior liquid extracts of drugs by providing maximum extraction with minimum amounts of menstruum and heat, and it worked.

The inventor John Uri Lloyd patented his first "Concentrator for Solutions" on Dec. 13, 1904. Several years later the New Jersey establishment of Johnson and Johnson aquired a special right to use Lloyd's cold still in processing their belladonna (150,000 pounds of the dried plant annually). In an article in the Red Cross Messenger of June, 1910, the use of this apparatus is described by this company as follows:

"It was found to be a process particularly adapted to drugs where it is desirable to extract and to maintain certain delicate medicinal constituents and aromatic principles. The Lloyd method, which was finally in an extended or modified form, adopted in our laboratory for the extraction of belladonna, is in brief a cold extraction and a cold distillation. In other words, the recovery of the menstruum entails but the briefest contact with heat, and when the recovery of the menstruuum is progressing even at the highest speed, the apparatus in not hot nor yet warm – IT IS COLD. The process of percolation, distillation, recovery and concentration continues automatically from start to finish. The liquid extract of the drug constituents is isolated from the zone of heat activity, is cold, and no air is present in the concentrator, ferments and bacteria are destroyed; thus fermentation and change is rendered impossible. The concentration is accomplished within a fraction of a minute.

"This latter fact is of the utmost importance in the extraction of belladonna, where the deleterious effects of the usual pharmaceutical processes requiring continued heat have heretofore been necessary. In the laboratory of Lloyd Brothers this process has shown remarkable results in the extraction of vegetable drugs, the results being markedly apparent both as to the quality and yield. Carefully conducted experiments in our own laboratory in the application of the process to belladonna, have shown that the complex plant compounds and structures are extracted unbroken. The final result is an extract of belladonna in every particular representing the whole plant. It is a concentration of the entire delicate organic constituents of belladonna, representing the plant energy in its entirety."

Though the exuberant claims of these manufactures of obtaining the entire plant activity in their extract by using this process can be taken as marketing hyperbole, it is evident that they were convinced of its superior results. This was also reflected in a letter written at the behest of Lloyd from F.B. Kilmer at Johnson and Johnson to Prof. Frederick Power, director of the Wellcome Chemical Research Laboratories in London, England, dated June 10, 1909. Kilmer described the device and method as "the most perfect that I have ever seen." It was used by Johnson and Johnson to produce 350 pounds per week of a solid belladonna extract. Even though the apparatus had a capacity of 6,000 pounds of dried belladonna, one of the advantages he noted was the small space that it required. In addition, whereas previously they had utilized three workers and an overseer to manage the work, with the Lloyd extractor only one operator was necessary, aside from occasional assistance with loading and unloading the heavy belladonna bulk. Kilmer noted the great reduction in alcohol loss, so that it no longer factored into the cost of the product. Most desirable was the extraction of 100% of the belladonna alkaloid content, compaired with the 80% previously obtained. The resulting product was distinctively like the plant in odor, taste, and other physical characteristics, in contrast to products made by ordinary methods. After examining other extracts of aromatic plants in the Lloyd laboratory, he also found them little changed and fully representative of the plant qualities. Kilmer recommended obtaining Lloyd's cold still based on both its economic and product quality advantages.

With the appearance in Remington's Practice of Pharmacy in 1926 of a description of Lloyd's extractor and instructions for its use, it became standard equipment among many pharmaceutical manufacturers for continuous extraction on a commercial scale. Over time certain drawbacks were noted. In particular, it could not be well utilized with mixed solvents, such as hydroalcoholic mixtures, due to the varying boiling points. However, it remains an important unit even to the present day for certain commercial extractions produced on a large scale. A seeming incongruity regarding this historical 100-year-old device is illustated at the University of Arizona. In the College of Pharmacy, along with numerous antique medicine bottles, an old nonfunctional unit is on display to illustrate an important development in the history of American pharmacy. On another part of the university campus in the College of Agriculture's modern bioresources research facility at the agricultural experiment station, an operational unit is currently employed for phytochemical extractions in association with arid land studies.

The Lloyd "batch type liquid-solid extractor" consisting of evaporator-concentrator, condenser, and percolator had been available in laboratory and large production forms from the Brighton Corporation in Lloyd's own Cincinnati, Ohio. [See below for more information on the manufacturing history of Lloyd's Cold Still.] The 5' x 3' x 9.5' laboratory extraction unit was obtainable in copper or stainless steel with a capacity of 1 cubic foot solids and 1 gallon concentrate. This lab unit is the one currently used at the University of Arizona, as well as at Eclectic Institute, Inc., in Sandy, Oregon. Eclectic Institute utilizes this equipment to reproduce several products reminiscent of some of the most popular remedies manufactured by Lloyd. The Specific Echinacea and Specific Cimicifuga (black cohosh, designated as Macrotys by the old Eclectics and Lloyd) are 1:1 strength alcohol-based extracts, while the Liquid Hydrastis is a 1:1 glycerine-based goldenseal extract intended for local applications. The introduction of such products by Lloyd and the Eclectics led to the wide popularization of these native American medicinal plant extracts and their current commercial success following adoption by European doctors and pharmacists.

[Editor's note: Unless otherwise noted in the article, resources for information on the Cold Still can be found in the John Uri Lloyd Papers at the Lloyd Library and Museum and in John Uri Lloyd: The Great American Eclectic by Michael A. Flannery.]