This receipt is for shellac, which Nikola Tesla used to seal wood and windings for air-core transformers in his magnifying transmitter in Colorado Springs.
Mr. Anton Hubner seems to have been one of Nikola Tesla's assistants in Colorado Springs. Mr. Hubner is listed in other documents as making payment for items for Tesla.
A receipt from the Continental Oil Company for paraffin oil. Nikola Tesla used this to seal his salt-water capacitors in his 20-million volt magnifying transmitter at Colorado Springs.
It seems that Nikola Tesla must have broken his watch or possibly hired the local watchmaker to assist him with some of the delicate instruments he used in his Colorado Springs experiments.