Sometimes dramming bottles or bottles for dramming units turn up and cause questioning among buyers. What are they? Perfume Shrine today aspires to shed some light.
Dramming is a term first introduced in the liquor business (hence Drambui, several hypothesize) specifically in whiskey distilleries as far back as the 15th century and dram might be derivative from drachma/δραχμή (Greek coin itself derived from δράττω, ie. grasp a handful) denoting amount of monetary value and thus specific volume. In some Scottish bars a 'dram' is taken to mean a large or double whisky and the fluid dram is one-eighth of a fluid ounce, hence "a small drink of liquor" (1713)  The term was also used as a an intransitive verb: 'To drink drams, to tipple' and as a transitive verb: 'to ply with drink'. Therefore dramming would be the practice of drinking drams of liquor. Free drams were passed around in distilleries to deter workers from pilfering.
On the other hand dram in the fragrance and cosmetics industryhas a different measure: a unit of apothecaries' weight, equal to 60 grains, or 1/8 ounce (3.89 grams) . Dramming is meant for "refueling" as in "Thierry Mugler's star-shaped Angel bottle has a dramming unit with an airtight canister that contains 16.9 oz of fragrance" (incidentally that's about 510ml)—enough to refill the 2.6-oz bottle six times".
Dramming is defined as: "A technique for transferring a fragrance from a larger container to a smaller one. When stores have “dramming events” they are telling you that they have very large bottles of the fragrance, usually on display, that they will pour into a smaller one for you, usually in concert with special promotions". However please note the term "dram" in the decanting business (collectors who sell amounts of their own perfume collection) as well as the US medical field is a different still small amount: 1/16th of an ounce.
Guerlain specifically carried the brown apothecary style bottles in both Eau de Toilette and Parfum de Toilette concentration, as depicted here in both Shalimar (in PdT) and Jardins de Bagatelle (in EdT). Some of these bottles turn up online or in auctions and garage sales. Their original use would be to fill up samples for customers or refueling splash bottles at the stores. Due to sheer volume and unfrivolous presentation they represent great value for money for the collector interested in the perfume "juice". It is however worth keeping in mind that several alcoholic products by Guerlain such as mouth hygiene products for gargling, hair oils (stilboite) and muscle rub liquids came in seemingly unadorned bottles, so as always attention is needed when purchasing or collecting.
Other fragrance companies also use dramming units, such as for instance the Bond No. 9 New York Chinatown Dramming Unit valued at $3500.
Let it be said in passing that dramming bottles also circulate for popular cosmetics and skincare.
Dictionary.comof Encyclopedia Britannica, 2008.
Thanks to perfumefanatic/POL for asking me the question in the first place.